Me and a couple of friends tried it a few times.
Solo it's worthless compared to other things in the genre, the Orcs Must Die and Sanctum franchises were way more fun solo.
Multiplayer it just seemed to be lacking something - like it was trying to do too much and only doing a half-assed job. I'd almost call it a collection of unfocussed minigames instead of a single game.
The other problems are that it was constantly (almost daily) downloading enormous patches, and that it looked/felt like an low-end tablet game rather than a PC game.
I'm sure it's fun in the right circumstances but why settle for a mediocre game when there are so many good
ones clamouring for your attention