I think peeps are fretting over this for little reason. While I agree whole heartedly that it is sub-optimal for Apple to shift a partly working device, it is an entirely different issue from antenna gate. Firstly, the antenna issue is common of many devices and will be on this one, flesh is not a good conductor of radio waves, never has been and never will be and this was not a fault of the device.
Now the tilt misread may well be a fault, as it stands, it is a fault. It may be a correctable fault via software, and apps such as iHandy clearly demonstrate that a calibration solves the problem in that app. It stands to reason (i believe) that a system wide calibration will solve the problem for the compass app and any other app that calls on the OS level orientation data.
If it happens that there is a hardware fault, then the warranty will provide a replacement, the 14 day issue is bypassed by a faulty device. I, for one, have notified Apple that I am unhappy with the issue, but am happy to wait and see how the thing plays out, that my consumer rights have me covered whatever the outcome. I have an excellent and beautiful phone in most respects. I have a third party level that will hang the mirror straight and if i am lost in the woods, the compass combined with gps will give me an accurate direction.
I am happy to keep my device and I think it is not good logic to rush to return your phone on account of the fault, as the situation stands now, where it is unknown whether it is a hardware or software issue.