Good for a little while...
Unfortunately, the game gets tedious by the final 10 levels or so. You don't suffer a real risk of dying, it just takes a long long time to wear the enemies down. I'm at level 50 right now. Probaly not going to finish it, just because its gotten boring at this point.
The troops you can train were hugely overpriced, since they die and you're out the cash that could be used to buy upgrades (in the early part of the game) or the better weapons and armor... Maybe if the troops only cost gems, rather than coin, it would allow you to use them effectively.
Speaking of weapons and armor, there really need to be a few more options. For most, there was only one version above the basic model (not including the mochipoints ones). A sell back option would be nice - as much so that scrolling the weapons isn't such a pain as to recoup a little cash if the weapon isn't what you are looking for.
I'm not sure if it was a bug or not, but crossbows didn't seem to gain the benefit of the cleave and critical hit skill - and couldn't be fired at all with the fury potion active. If they aren't bugs, they should at least be documented in the game instructions.