Bland
I like this style of game. Problem is this wasn't done well. Animation and graphics could use some work. Adding a larger variety of music could be good. Heck, environmental effects would make the game interesting as well. Ever play Fire Emblem? Rain (and I think snow) were great ways to vary up strategy.
You should be able to upgrade or heal in mid battle. Also, you should be able to bring out additional troops. The 10 limit is kinda lame. Also, a little annoying you can't spawn (like) five archers faster because the cooldown prevents you from summoning more of one type of guy per second. So if you want your numbers up, you have to add variety to your troops. While I like variety... some of your other units just plain suck. Why bother?
I dunno. I like the concept, but it isn't anything special and these minor complaints don't really help it either.