What's the point of the strongholds having hp? If their troops are all dead you should win the battle rather than having to click and wait for the tediously long animation for minutes.
The rewards are terribly balanced: You get 24 exp and 1400 gold for beating a weakling monster of your fellow trainers, and beating the tough guys in championships only give 8-16 exp?
My tip for too many enemies: Crashing into enemies doesn't hurt THAT much. You can ram through half a wave of fireflies if you have full health.
And for upgrades: Buy the cheapest one at any given time... that does you the most good.
The trick to expert zombie defense is to make matches near the bottom of the board, that gives you more chance for chain matches. Also, use scramble board often.
A PASS button would be good when you know that the only move left on the board is to give your opponent a big special attack. What we can do now is to wait for 20 seconds -_-
Would be more fun if the enemies have better AI, rather than just moving horizontally and ONLY shooting vertically. And why are the bosses NEITHER smarter nor tougher?