Tip: Look through all the Kongpanions in the TV screen, on the end of the skill tree. If you own one, you get a 2x bonus, 3x for a golden Kongpanion :D
The levels become too hard too fast at some points, even if I've got all 3 stars on the previous levels and used up all my upgrade points :(
Still, It offers that challenge to the game that makes it interesting to play :D
They should add another set of upgrades for the hero after the story and after the extra stages because it seems like the hero becomes one of the weakest in the team after you get stringer units