Pros: Easy to learn and jump into. Interesting blend of defense and tower defense. Upgradable skills with a reset button also a plus. Nice variety of enemies (I friggin' hate those slimes...). Being able to replay stages for level grinding also a plus.
Cons: Little simple, not having many types of traps or weapons means not many different sets of tactics; every battle was arrows, cannon, arrows, ice/fireball, repeat with trap building between waves.
Other: The fireball/iceball combo was a little neat, but tricky to pull off unless you devote lots of points into both skills; be neat to expand on this idea for other tactics. All in all, it's a pretty good game. I can see the influence of a few other games here (probably just coincidence though), but not in a bad way. Could greatly expand on this game by added several traps, weapons, skills, but as is, it's certainly not a bad game. I like it.