Only missing bells and whistles
It has good mechanics, bearable graphics, and pretty much everything you would expect from a game like this, so kudos on that. The thing that keeps this game from being really good are a few balance issues. For instance, you don't level up after the first wave, so you go to the screen with no points to spend and little gold. Also Meteor and Venom are never worth getting, you could have four ranks in the arrow spell before you can afford meteor. It should be made cheaper. Venom would just need a revamp. Other than that, tiny things like a tutorial level, an intro movie, maybe some minor menu tweaks, would all add to making the game feel more polished and add replay value.
Overall, its a good start. Keep up the good work.