On iOS 7 beta 6 on my iPhone 5, the level in the compass app is really weird, sometimes it will show -1 even though the surface is in fact level, confirmed by my iPhone 4 (also on beta 6) and a physical level. Sometimes it will show that the surface is level, but sometimes if I put it back on there it'll show -1 again. I noticed it works a lot better without my case on, which is just a cheap rubber case I got free with the phone. I don't like putting it down without the case on because it gets the back all dirty and I'm paranoid about back scratches (I don't want another metal back iPod touch again *shudder*) and sometimes if I tilt it until it is at 0 degrees and set it back down it will stay at 0, but this doesn't always work. (Sometimes it will never go to 0 ) And on a somewhat unrelated note: What is that second mode in the level that's red and turns off after you tap on the level? Does it have any function besides a different look?