This game is cool and all, but there are bugs, glitches, and concerns which need to be addressed:
First off, I don't like the fact that you are stuck playing as "Davion" and you can't select to be any of the other characters, and I don't like that you can't customize upgrades very much.
Second, I can't find the "instruction page" anywhere to unlock the corresponding achievement.
Third, sometimes the enemies freeze in place (except for walking animation) and sometimes one spawns which is invincible which doesn't allow you to clear the stage so you have to restart it.
Fourth, completing all the sidequests is mostly pointless except for gaining a little extra money which later on in the game doesn't really add up to much to buy the very expensive upgrades. Personally I would have made it to where completing sidequests unlocks runes as the main quest progresses and you can keep the runes permanently... but that's me.
And finally, the final boss. Once you fully upgrade your party and purchase all runes, he is fairly easy at first, but it seems like when you get his life meter down to the last few hits, he gets really cheap and instakills you without warning. There were even a couple times where I "won" without actually finishing him off.
Overall the game is okay. It's just a generic run-of-the-mill action game based off of other, more popular action games, but still captivating and fun, however said issues can get aggravating.