I've tried all three steering options:
Camera - I find the worst of the three, moving the camera conflicts with the whole idea of AR and being able to look around the level, so I find that one clashes with the other.
Joystick/Touch - picking between these two is tough, I like the touch control a lot but because I'm holding the iPad with one hand since this is an AR game and then using the other finger to control where the car goes it can get tiresome to hold the iPad with one hand. Joystick is OK since you're already holding the iPad with both hands but not as fun as touch. If I had to pick between them I would pick joystick though since holding the iPad with one hand won't allow player to play for long.

Couple of other suggestions. In the main menu the car can be moved around which is cool, but I found that out by accident. Should have a flashing semi transparent text flashing from time to time something like "Touch to move car" or something similar, also moving it around should move the car in that direction not on top left/right corners to make it go backwards. This is a menu though so not a big deal, but if you're going to go through the work to make that kind of menu I would make those changes to make it cooler.

Lastly the tracks, for test flight you guys should unlock all the tracks so people can try them. I only played the first one but had a quick look at the layout of the others in the menus. I would consider adding things to tracks like fire rings you have to jump through or some collectable items to pick up, etc. Perhaps that's in the works, I don't know. Anyways that's my 2 cents.

Few observations:
- The menu system could use some work graphics wise.
- The tutorial is a good idea but the fact that it stops the game while you're playing it really breaks the flow of the game. Perhaps some exaggerated way filling in the health bar if you're over the recharge pad, or just a quick tutorial or graphic at the start of the game that explains what is going on. I found the tutorial to be interrupting the game and a bit annoying.
- I like the mechanics of this game but I think it would work better if aiming worked differently. It is very hard to aim in 3d cordite system the way it is now. I would try to have the ship shoot straight and to the centre of the tunnel so just up towards the centre to see if that would work. As it is now it's too hard to aim. Or perhaps some kind of auto aim/target lock mechanism. Shooting the ships is great but turrets when ship is at the other side of the tunnel not so much.
- Lastly, the graphics are not cohesive, the ground doesn't really match the graphic style of the ships, you might want to look into that. Maybe making the ground more toon style would work better. Don't get me wrong, the graphics are not bad just that I'm seeing a disconnect between the environment and the ships that are flying in that environment. They don't seem like they belong together.

Over all very promising game just needs some TLC. I hope you don't take my criticism the wrong way, I really like the game. Just trying to help out.