I've only played the first few battles so far, but this looks great! On first impressions, I'm liking it a lot.
I couldn't initially figure out how to choose a different Hero; ended up with the Warden, I don't recall being given a choice. (If I was, I missed it.)
Could do with some more polish on the UI, but not a deal breaker.
On balance: Hard to say so far, have only played Warden.