I really don’t like the new Watch OS.
I don’t like that you can’t swipe between watch faces anymore, or that you can turn the Digital Crown to enter night mode. Does anyone know if there are any settings to get around these (for me) problems?
At the moment, I’m not a fan of the Smart Stack, but that might change. Any tips on how to customise it?
Watch OS 10 is the first big redesign of the OS as far as I am concerned.
It definitely needs time to get used to it, but so far, I am quite impressed because WatchOS 10 does provide me with more options to control my watch in this small user interface. I like it. Smart stacks can become very powerful if the OS or third party developers are doing it right.
Regarding night mode:
I did not have the time to dive deeper into WatchOS 10. Maybe there is a setting turning off this automatic behavior? I have no idea.
EDIT:
I appreciate the change because I have changed the watch face inadvertently multiple times. 
The new way:
Touch and hold the watch face, swipe to the one you want, then tap it.
I downloaded the beta about a week before the final OS came out. I hated it during the first few days but it’s grown on me a lot.
I didn’t originally like the remapping of the buttons, and I thought smart-stacks was poorly thought out and a feature I’d never use.
I’ve gotten used to it though, and a lot of third party developers (Carrot, Fantastical) have rewritten a lot of their UI to make things bigger and more grown up – as @anon72922636 mentioned in an earlier post.
I find myself using smart stacks as a quick way to log a workout. I used to change to the “Activity” digital watch face whenever I would go for a run or walk the dog, but now I just use the crown and scroll to the bottom of the smart stack screen and there is my workout app.
Any new system is disorienting, but give it time. I purposely did not install the betas over the summer (first time ever going from old public to new public releases without installing the betas), and initially I was a bit lost. For the first 10 minutes or so using the watchOS upgrade I was just poking around, seeing what got moved where, and was baffled as to how to swipe between watch faces. By the way, I appreciate the change with that feature - do you know how many times you can accidentally switch watch faces by wearing a long-sleeved shirt prior to watchOS 10? (Hint: endless amounts).
I’m still waiting to see how much battery life has been traded for the fancy new graphics.
Does anyone know how to change the app in the Dock? I can’t find the setting anymore
AND,
reduce some those unnecessary transitions
This was my biggest complaint, but I got used to it.
My red dot notification indicator doesn’t seem to want to go away, even when there are no notifications. I’ve tried turning it off/on in settings.
Anybody else seeing this bug?
I refuse to upgrade if I’ll lose the ability to swipe left and right for different faces. That’s my single most-used feature of the AW after the time itself.
It’s still very easy. Just press and swipe as before.
They have changed my beloved timers app 
I’m sure I will get used to the change, but I suspect I will have a frustrating few days as I figure out navigating the new menu.
It’s also probably going to be a frustrating few days not swiping up in order to set the water Lock Screen with wet fingers 
I’m trying to understand the reason Apple remove these gesture based triggers. Before, you swipe up for the Control Centre. Now, you press the button for it. Were there many cases of reported accidentals swipes that caused confusion when watch face change or control centre appears out of no where? Otherwise, why made such a drastic change?
Sad to say you are stuck then (at least for this OS upgrade). I think that’s a bummer reason to miss out on the other niceties of the OS this go around. And as others have pointed out, swapping only take a moment longer now than it did before.
I for one am glad I won’t accidentally change watch faces anymore
I happen to like the new watch OS. The rearrangement works well for me. I also have problems with the watch face accidentally switching, so the new interlock solves that problem.
I am enjoying most of the changes, but this is a huge disappointment to me, too. I know you can press and hold, but swiping was fast. I used faces as an app launcher of sorts, with commonly used apps in complications on faces to the left and right of my main face.
I am in love with the new Watch OS. Finally the watch is able to show data without digging into respective apps or multiple clicks in the weather app.
I have put up tons of widgets for Weather which were generally buried under the weather app. No longer I have to go clicking around in the weather app.
As a 55 year old guy who grew up reading every Peanuts book and watching every TV show and movie with my dad (passed in 2017 at 90 years of age), may I say I absolutely LOVE the Snoopy watch face 
For me the biggest issue is they have moved the “water lock” button out of the workout actions, I need this button to lock my iPhone when I’m at my kickboxing training, else I’m pressing buttons all the time with my wraps.
After I installed the beta, it did take me a while to find where they had moved it to. Why they couldn’t leave a shortcut in the workout actions I’ll never know.
I’m loving it. Finally it seems like the space is being used well. The widgets make it easy to surface information from my most used apps on a tiny screen and my run is a tap away.
Changing the button action was rather daring, but works for me now I’m used to it (I use it all the time for focus mode) and it will be more intuitive for new users.
Finally, the app redesigns were well overdue.
I’ve set up my widgets today and I do think it’s weird that there isn’t a widget for Home, even though it’s a native Apple app. Why would they not build support for their own software “straight out the box”?
I thought I’d cheat my way around this by setting up a shortcut to open Home via a widget, because Shortcuts is supported by widget, but it seems only some Shortcuts are loading as available widgets currently so I couldn’t circumvent the limitation that way. The list of available shortcuts is really random as well - I have a shortcut that has over 70 actions, all related to an iPad task, which the watch is offering as available for a widget, and yet a simple shortcut to turn on a light is not presenting as an option. 
(I have not run the iPad shortcut on my watch, this seems like an insane option and quite likely to crash something!)
I then thought I’d circumvent this limitation by using the app list. I keep my apps on the list view, and previously it remembered where you were in the list (I was usually near the bottom hovering over the Timers app). So I scrolled to Home and left the app list there, figuring that would be the quickest way to access it. However I’ve now discovered the app list resets to the top each time you open it, so you can no longer leave it hovering over an app. Not helpful.
I’d actually love for Apple to just let us remove ALL apps we don’t want, even native ones, from Watch. I only use like 3-5 apps on my watch. All the rest of that list is basically rubbish I don’t want.