I switched from Zsh to Fish a week or so ago and haven't regretted it yet.
As @Matter said, it's not to hard to get Zsh set up pretty similarly—I'd previously done that, so it wasn't a big change/improvement for me. But no issues or complaints, either.
(The main reason I switched is that it's much easier to script/extend, which I'd like to do more with soon. I haven't done much yet, but just in configuring it I can see the power. It's also way snappier to start, a nice bonus)