Definitely a 5 star game. Normally I don't 5 star a game that uses Kreds but the premium content is superb simply because the makers haven't gone overboard with wanting a person to spend 100's of Kreds to get everything. 5 Bucks or 50 credits is well worth getting all the premium content.
Way too many problems with this game. Problem one XP is unbalanced. Problem two most of the towers are useless. Problem 3 if you reset your points to try something new, and instead of reseting them again and load are previous file so you don't have to chose everything over again... all your points are gone, but you're the same level. So 1/5 from me.