Jetpack Joyride

The Good
I thought the missions would keep coming and never end. In fact, there are only so many missions. None of the missions are too difficult. The difficulty is very fine-tuned. The most difficult mission is one of the final three missions. It'll likely be the last mission you beat, and after that, you'll realize the game actually just ended. It's a good moment that brings a sense of conclusion that endless-running games rarely do.

The Bad
First of all there are problems in the algorithms that negatively affect your missions. Not too serious, since the missions are still beatable.

The achievements require too much money. You either have to buy coins with real money, or play the game more than you should. I say just forget about the achievements and complete the missions.

The Bottom Line
It's free when I got it. It's free, it's short, and it actually has an end (unlike Temple Run). It's a complete gaming experience.