What Makes It Special: There is so much polish and so many "that's clever" moments that this game, as a package, is one amazing and potentially one of the best distance games ever created. The graphics are crisp, clean and cute. The little touches to the graphics are excellent (example: the animation differences from when you're running vs. when you're flying). They also use some kind of physics engine when you don't really need one. What this equates to are fun animations and endings, like your hat flying off your head when you crash or the wall bits blowing apart when you start the round.
Outside of that you have a store that allows you to change jetpacks, use powerups, change your skin and access both Game Center and OpenFeint.
The most important part about this whole experience, that I think they did wonderfully, is that they separated "achievements" and "missions". The last time I saw a distance game do this was in Tiny Wings. You basically provide missions to the player so they have another way to approach the distance game. Getting the furthest distance is no longer the only goal when you incorporate missions, which could be "high five 25 scientists in one round" or "crash through the wall 10 times". Your goals have changed and thus allow you to change how you play the game, which adds challenge and variety.
This is also interesting because of how they distinctly separate this from the "achievements". The achievements in the game are sometimes related to the gameplay, but are presented in a way where you can do them at any time. They're not your current goals to reach the next rank. They're like secondary missions and objectives that you can do in your free time.
It's the way they approached the distance game and packed enough goodies in it that really make this game worth that whopping $0.99. Sure they have in-app purchases, but those things are basically money cheats that give you a bunch of coins without you having to earn them with gameplay time.
Gripes: The only gripes I have with the game are weird pauses you get when the game is trying to connect to Game Center and your phone's reception is shoddy. It stutters the game and while this isn't the fault of Halfbrick per se, it's still annoying. Also, you tap the screen to make the gentleman fly. What happens for me is I use the right thumb to do this and can sometimes obscure incoming obstacles, like the "!" indicating incoming missiles or a fast approach rotating zapper line. Again, slight annoyance, but nothing to sour my experience.
Rating: Highly recommended.
Purchase: Jetpack Joyride on iTunes