The main problem for me, is that it's too easy. I don't play tower defense games, so I'm far from any kind of expert in the genre. Yet in this one, I ran through the game on the hardest setting rather easily. I still had fun, but it was just too easy and too short, I think it only took me a few hours to go through it on the hardest setting(it's been a while since I played it).
I liked it for it's theme of Two Worlds mainly, and it was a fun time when I played it, but I was kinda disappointed overall.
I'd recommend it if you're a Two Worlds fan, it has a tiny bit of story to it, and you get to play a tower defense game in a Two Worlds setting, but if you're an expert at tower defense games and want a challenge, this wouldn't be a good choice I don't think.