Love pangolins and love tower defence games, and this one was decently fun for me. That being said, there seem to be a few significant problems.
There doesn't seem to be a reason to buy anything other than the basic rocket turret until you get to the point that you have to place them so far back that they're not in range, since nothing else does enough damage to make up for its cost. Mines should do a lot more damage, since they're one time use. The high caliber turret fires so slowly that it only ends up being half as effective as the basic rocket while costing twice the price.
I think it would be better in level 2 if the first few waves alternated which side they were on. It may be a little annoying for someone who's new to tower defence to place everything on one side, only to find there was a second side, but since it's early in the level, this wouldn't be too frustrating, as they could quickly try again without losing much progress.
The sides seem to be uneven on level 2, which isn't too much of a problem, except that one side definitely ends up with a lot less turret space than the other. Uneven terrain mixes things up, but take care not to let this make one side weaker without making the parts of the waves that go to that side weaker as well.
Doing as much damage as I think was possible, it was still impossible to destroy the enemies on waves 25 and 26 of level 2. It would be very unfortunate for a player to have lost 2 eggs a lot earlier, and get to the end only to end up losing arbitrarily. Moreover, I think going from introducing that tanky of an enemy to having two of them show up (with the sides being uneven) is not really fun. It would've been more fun if one side got the tanky enemy, while the other side got just a huge hoarde of enemies.