I have a large Flutter codebase and I don't have the same opinion, Flutter web is still an alpha quality and it would take way too much work to make my codebase work with the web version. For desktop though, it's pretty good.
I've built a new Flutter web app this week and I've hit some gotchas like improper rendering of text form fields (SVG flags were incorrectly set when displaying on the web, regardless of HTML or Canvas rendering it seems). However, Google engineers are actively working on problems like these and it seems like the dev branch is fairly stable and usable as of right now. I'd say 30 days ago it would not have been the case.
