joppo: Your recommendation would be a bit short on time but it's not a problem, I bought the game a few days ago. But thanks for your insight.
In fact you have me even more interested now that you mention that the game got tougher than it used to be.
bluethief: I mentioned a few posts ago, but if you like achievements, know that for this game they're all completely broken. It's a shame, but it doesn't lessen the enjoyment you can have with it.
I agree with MarkoH01 on the first boss being unnecessary difficult, but I found the last boss to not be that difficult. As a tip: just keep on moving and use the last weapon you get on the game!
Thanks. Sucks for the people who want their cheevos, but luckily I'm not one of them (except maybe when they're in the game itself, like in Kingdom Rush, and earn you some reward like a small ATK increase).
Going by your tip I suppose I will be okay against the boss as that's my most common strategy against bosses in these games.