Initially there are a lot of freebies for you to blast through a lot of levels. Around level 125 that stops and then there are levels that are just painstaking grinds. An ultra hard level with no boosts is an exercise in futility and seems to be made to make you pay or have progress completely stop. Also, I've had a couple of levels that require a certain number of bottles to be popped but the last bottle would not appear. It caused wasted lives and lots of time. Will uninstall soon.