Now that we have real reviews I wanted to give this game a better response.
As a long time tower defense player, I have to say this game is in the top 3 of all time. I'll try to explain why I love it so much, and why I'm so excited for the sequel that was recently announced.
This game provides somewhat traditional mechanics if you're familiar with TD games. Players can build units on the perimeter of the path only, so there is no blocking/routing mechanics to worry about. Unit's have different attack types that are better and worse for some situations
What is unique about this game is that units level up in a persistent manner between levels, allowing your units to grow over time, This included an entire skill tree for each class of units that can be customized to your play style. Additionally, units have a weapon and armor equipment slot and the game does a good job of making this meaningful by introducing rare equipment a bit later in the game.
Levels are replayable so you can grind your team a bit if you feel a little weak or would like to beef up a bit before a boss level. To compliment this aspect of the game, each level can be played on different difficulty levels, which provide bigger rewards at the cost of a higher difficulty. This aspect of the game kept me going back and trying to beat my records and old levels in order to get some of the better rare gear.
Lastly, the game features a fast forward mode which is a welcome sight for those who play a lot of tower defense games. It really helps grinding out those later levels.
It's rare for a TD game to have an in-depth story, but Defender's Quest does a great job with this. It's not ground breaking, but it certainly sets a nice tone and even introduces a bit of moral dilemma that plays into the unit mechanics later in the game. I won't spoil it, but I will say that the level of narrative impressed me, and kept me engaged until the end.
All standard stuff here. You can look at the screenshots and get an idea of what you're into. In general I'd say that the graphics do a good job of matching the needs of the gameplay, and the animations are smooth and crisp even during hectic late game levels. The graphics change into a pleasant style during story segments and do a good job of relaying the emotion and facial expressions of the characters.
All in all, this game really scratched a Tower Defense/RPG itch that I'd been craving for a long time. If you can pick the game up on sale and like TD games I'd recommend buying it without hesitation.