Not yet. Or rather, I would say you can use it for simple stuff, like Etcher then it is a reasonable choice. But you wouldn't want to use it for something like Slack yet. Some basic stuff like ctrl-Z in text fields does not work yet. Doing normal desktop things like menus and file dialogs will be a pain.

That said, I am writing a Git desktop client in Flutter and I like it. But I don't expect to finish it for many years so hopefully by then they'll have ironed everything out.