I am also using eero, and very happy with it. It has been fast and reliable. The iOS app is easy to use.
It does not support WiFi 6 as others have noted. I assume it will not in that presumably a hardware update would be needed, so when WiFi 6 becomes a “thing” (eg my other devices support it, which none do as of yet) then I would need new hardware.
Configurability is limited; you can set up port forwarding and dhcp reservations, for example, but you don’t have the wide range of configuration that other vendors allow. That can be viewed as a drawback or a positive depending on your perspective.
One thing I did like is that you can configure with wired backhaul just by plugging into your Ethernet backbone; I have seem that some mesh systems require you first configure via WiFi and then convert to wired. Probably not a big deal in the long run, but just a little convenience.
As @tjluoma noted, if you subscribe to eero plus (they have a new name for it) at $99/year, you get your Malwarebytes, 1Password, and encrypt.me subscriptions for free, which is a great deal, especially if you were already paying for 1 or more of those on your own (which I was).
As far as VPN support, they do not have it built in. Outgoing VPN is handled by whatever service you use, whether encrypt.me or otherwise. If you are looking for incoming VPN, you have do do that another way. I have a Synology which is my incoming VPN server. You could easily build an inexpensive VPN server with a Raspberry Pi if you are so inclined.
Recently Linksys released their new Velop system which supports WiFi 6 and which looks very capable. I have not seen any real-world reviews as of yet. It’s expensive, at over $600 for two units, and in the absence of any WiFi 6 enabled devices, not worth that cost to me at this point. I expect by the time I have enough such devices to warrant WiFi 6 networking, there will be lower cost options available as well.