I like it. It's a fresh take on Tower Defense, basically giving you a limited land on which you can build towers in the middle and then having the creeps flying up to your ship in pre-set waves. Just enough story, upgrades, and variety to make it enjoyable.

The negative is there is no action-while-paused and a ton of micromanagement as lots of your towers have a direction they are aimed in and you need to manually change that. So it's very hectic and very busy.

I am 4 missions in and it was worth my money so far. There is a lot of micromanaging and it's quite difficult. Won't be a marathon 'till it's done game, but more of a mission here or there palate cleanser after Diablo 3 leveling runs.