Pretty fun game so far, been doing runs in endless mode after beating the main areas. That said, the way the skills are set up makes it look as if they were meant to be taken in order, but I could choose among any of them so long as I had the points. Not sure if that was intentional or not. Also, in the end-game you tend to make a lot of junk gear in order to raise your forge level. It might be good to have some way of quickly smelting larger numbers of low end gear or something.
I'm not sure about the game balance, as I haven't played too terribly much yet. From what I did see, melee options seem a bit weaker than range options to me. Once I swapped to mage/archer, I was able to start wiping out waves much more easily, and made much easier progress. Still, that might be a playstyle issue, so it would need further testing imho.
Overall, a fun horde survival game, already up to 4 hours on the game.