I used LastPass for roughly a year before making the switch. I also switched from Chrome to Firefox at the same time, on Windows and Android. Desktop - no issues!
Android is evolving, and their changes seem to have put Firefox in a slightly behind position, which I think they're almost caught up on. Basically, there's legacy and modern autofill capabilities in Android, and Firefox is working on closing the gap. In the production release, I am unable to use the BitWarden android app, but there's an add-on that mostly does the job.
I have two issues with the add-on. First, it tends to disappear from the menu. There have been some bugs on BugZilla for this, including one I recently submitted. Of course, quite fortunately, I haven't been able to reproduce the issue since I submitted the bug and installed Nightly. And it's interesting - Nightly seems to work with the app, so the need for the add-on should go away. Second, the add-on is a little clunky. It opens a temporary tab, and then closes that tab when you select your login. However, there's an issue there, too, where sometimes it just does not work. It throws up an error message that it's unable to autofill, and there's little you can do about it except close the temporary tab and the original tab, and start again.
The Android app also has an issue that I've seen with Chrome, where it isn't actually detecting the site you're browsing, but just the app you're using (Chrome) and thus is unable to select your login. This is easy to get around - usually going back to Chrome and then tapping the BitWarden toast will find you your login.
Overall little nuisances that are mostly Android related issues more than anything, and each of them seems to be getting worked out, so I expect the user experience to only get better.