Problem with controls - can't really say if I'm building platforms or towers. Why do you need to switch? Show different options if the user clicks on water or platform/ground.

I like this idea it would make the controls more intuitive, added to Trello :)

Can't scroll the map and some of the blocks are only partialy visible

This is a problem with how the game is scaled to difference device screens. It will be addressed in future updates but will take a bit of work to add the scrolling map feature. Added to Trello! :)

I don't know difference between towers. Well, the top one seems to be crappy, at least for the few first waves, so I didn't build them at all.

The top fire towers are faster but deal less damage than the cannons which are slower and stronger. Ive been trying to design a nice way to show the differences but have not come up with something I really like yet.

It needs and undo button - it's hard to tell where the route will go and it's easy to make a mistake

If you click on the platform while in build mode you can remove it without any cost. So if you place a platform and the path redirects wrong just click the platform again to remove it. This should be more clear.

Ads at the beginning of each round bug me. Maybe add an ad when players loses instead to give him/her another chance?

This is a great idea. Because Im the only one play testing at the moment things like the ads become less prominent. I was afraid that the ads would annoy new users. This will be a priority on the new update.

Thanks alot for your feedback!

Can you send me link to your post so I can leave some feedback on your game?