I am usually highly interested in power-user, scriptable, highly customizable apps.
As such every time I read about Omnifocus it sounds like I ought to learn it. But then I look at Omnifocus and it seems so basic and not really different than any other To-Do or project app.
I must be missing something.
Can someone post an example of the sort of thing that you can do with Omnifocus that you cannot do with other apps and which makes it so powerful?
OF is the best GTD (getting things done) adjacent work management system there is. You can use it in loads of different configurations from the most simple (task management in one single list) to hundreds of projects in many different function areas, but where is most sense is where your task management system is based on GTD.
The main feature which OF has which no other apps have (that I’ve seen) is Review. This allows you to set a review timescale on each project which brings it into the Review feature when it’s, this can be every day, once a week, once a month… it means that even if you “forget” about a project, it will fall back into your view at a timescale you set (or the default) sooner or later.
Review is the most important part of any GTD system, as it means that you regularly understand what’s on your plate and can take control of your workload, pausing projects, tracking things you’ve delegated to others, cancelling projects which no longer make sense.
Lots of apps lets you setup multiple projects and tags, but once you get over a certain volume, it’s easy to lose sight of projects.
I’d say there is real power in OF that is a level or more beyond most task managers: for example you can set a project to be sequential (you have to finish tasks in order) or parallel or a simple dump of tasks AND you can set subsets of tasks of your choosing within any of those projects to be sequential or parallel. Projects can fully reflect reality from just a list you check off to a more complex structure where some tasks depend on others and some can be done as and when you wish. You can set completion or defer TIMES as well as dates and you can even set them in particular time zones. Tasks can be “available” (ready to be done) or “remaining” (still needing to be done but maybe waiting on something else). You can pull lists into almost any order you like. Projects can go into folders, which can be nested as you like. Custom perspectives (which allow you to construct lists of tasks or projects by filtering them by all sorts of criteria) are like nothing else I have seen.
Of course, the cost of this is that OF is busy, hard to break into, has a steep and long learning curve and is not intuitive. It demands more work and commitment to use than might be helpful if you do not need its power. I’ve always found it really ugly too and the UI is very cluttered. There are weird things you can’t do - e.g. in filtering tasks for perspectives. You often feel that you can customise everything except what you really want to. I am more than slightly disappointed that the new version does not go far enough to address these issues and I hope the team will use the major re-write to start doing that as soon as it is released.
Having said that, when I was CEO of a large educational institution (300 staff, 2000 students and £8M annual budget), I could not have coped at all without OF - I’ve said that it saved my (working) life more than once. Things to think about and do were coming at me fast from all directions and missing even one could have serious consequences. People would mention something in a corridor that just had to be dealt with, but not necessarily at that moment or simply. The system I had set up in OF meant that when my main perspective was empty, I could trust it, go home and relax at least until tomorrow, but other perspectives showed me instantly and days ahead when I had to re-plan and re-prioritise and made me very good at blocking quality time to think and get things done ahead of deadlines so I had capacity to deal with what came up. A couple of checks a day was enough to keep on the rails. I knew I had everything, because it always went straight into OF, and that it was soon planned and would almost certainly get done if it was important, even if that meant dropping other less important things. I have never found anything remotely as capable of juggling too many important demands.
I’m mostly retired these days and my life is nothing like as complex, and my daily work has fewer serious consequences, though I’m still busy enough. OF feels like too much for me right now: it’s overkill and I really don’t need to do more than a quick look every morning and a proper look on a Sunday, but when I had first moved house and was juggling contractors and tasks, I went back to it. I’m using Things (which I had before OF) and it’s comfortable, but I often wish I could apply some OF ninjitsu to sort a few areas out!
I wrote a piece on my blog a while ago about my relationship with OF and Things
I had the same experience when I was General manager of an IT company, without OF I would have failed, hard. No other tool I’ve tried has come close.
I wrote an article on What makes OmniFocus unique? that summarizes features that set OmniFocus apart from other task managers.
A few of my favourites are defer dates/times (it’s very helpful being able to control when a task becomes available), the Review perspective (I have yet to find another app that provides a simple, systematic way to review projects) and Omni Automation (I share some of my favourites plug-in on the OmniFocus Plug-In Directory).
I’ve switched to Apple Reminders after years of using Omnifocus. The two things I miss from Omnifocus are the more robust review functionality and, even more so, the ability to repeat a task a set period of time after a completion date, rather than after a due date.
I appreciate the many responses - very helpful
Question - many of my to-do tasks arise from email. I use Office 365 webmail; my mailbox size is impossibly large to sync it to all of my MacOs computers.
What is a good way to automate converting a web email message to an item in Omnifocus?
Omnifocus has a built-in email-to-Omnifocus gateway. If you’re automation-friendly, look at Joe Buhlig’s Omnifocus automation scripts:
Using those, with a bit of initial fiddling you can email something into Omnifocus and configure all the tags and such right in the email subject line. That plus a Keyboard Maestro macro to provide a friendlier frontend to the syntax can be incredibly useful. 
Hookmark can help here, if you have it.
For example, I invoke Hookmark the email, press Ctl-n and a new task is created in the OF inbox, automatically linked to the email, which I can then archive.
I find that’s enough and haven’t really delved into the cleverer fringes of automations yet…
I think you have DT3 as well, don’t you? If so, you can create OF tasks directly from items in DT3, and using Hookmark, can create and link OF projects to project support groups in DT3.
Thank you @webwalrus
I see also that OmniFocus can be connected to Zapier
Perhaps this is worth looking into more
Appreciate the help from everyone
I’ll piggy-back off Richard’s request: what are people’s views on the web app.
Like Richard I use M365 at work. It would be good to have desktop functionality so I’m not switching to my mobile/iPad every time I need to add a task (email to OF, excluded). I’ll also investigate Zapier.
The web view is ok, just nowhere near feature complete, so would not work standalone.
I’d add “Perspectives” to the Review functionality, plus the implementation of “Defer Dates” which make it different to other apps.
I survive each day by being able to click my “Planning Perspective” button which will then only display those tasks that are currently doable. I review this and choose (flag) which tasks I am going to complete today. These then appear in my “Daily Execution Perspective”. By doing this it hides all the hundreds of projects and tasks that I am intentionally not interested in that day.
I’m curious, what note app do you connect to OF for tracking project information, meeting notes, etc?
For work related stuff I continue to use Roam Research as I have for the past 3/4 years - obviously no direct links between OF and RR or vice versa, but I don’t need them.
For everything else I use Obsidian (notes) and Devonthink (resources) - which I can obviously link to and from OF where I need to; but to be honest again I don’t really need them, as “Search” is so quick/easy to use.
Another GTD focused app with Reviews and Deferred dates etc is MyLifeOrganized. I was a user for 15 years. I don’t use a todo manager anymore.
MLO is subscription free (there is a sync service).
Out of curiosity, did you just use it on Windows? Or did you do all your task management on mobile?
Looks like there’s not a native Mac version, and despite their website’s suggestion I’m not keen on installing a virtual machine. 
I started on Windows with version 0.8 and have used everywhere since. You can run the windows app on top of the Wine emulator and I did that for a while,
FWIW the iPad app is solid too.
MLO was great on Windows. I liked the way it handled dependencies. I switched to macOS around the time he released the iPhone app and helped to test it.
I think Andrey could make a really powerful Mac app; he would struggle with the look and UX conventions if he didn’t hire a designer, though.