Great music and graphics! It's a satisfying tower defence game that provided plenty of time to build up units while providing more challenge with each wave. The Next Wave button also helped to provide some additional difficulty or just to rack up more coins for towers quicker.
I would have liked to new tower types unlocked sooner since there is an impressive amount of content that just needs more time to get to. But other than that, it's super polished and has a ton of gameplay!