5 stars: This is one of those few rare games nowadays that DON'T shove an ad in your face every time you finish a level. Getting gems is also easy if you play regularly, and the difficulty curve is constant which makes the repetitive, but sort of satisfying, gameplay still engaging even after having played for a few tens of hours. That being said, I haven't had to spend a penny!
4 stars: Great instalment in a series with great predecessors. Good sound design, exciting visuals, solid upgrade system, daily and weekly new content. It's the casino-like experience in a casual mobile game. Ads only to enhance gameplay, otherwise you don't need to see a single one. Masterpiece in addictive game play.
4 stars: Really cute game; it's fun for a short time waster. I like being able to collect different things and upgrade, but to really get decent stuff, you may need to spend money for upgrades. It gets repetitive in terms of gameplay, and without real money, its slow to obtain gems and upgrades. I will state that it is a decent game, its free so can't complain.
3 stars: Really fun game, would be immeasurably improved by actually being able to play it for more than about 10 minutes at a time. Even with the first cap upgrade the energy system is just too stingy. Something like a zero-cost, zero-loot mine that grants energy for reaching the idol could go a long way to improving the issue, without hopelessly unbalancing everything? Right now it's mostly a game about waiting.