I have one of these
i also had a iPhone4 version before it and found it quite good.
the 5 version doesnt have any access for charging unfortunately, but works well as far as handlebar mounting etc is concerned.
I didnt end up using it for navigation on a recent trip like I though I would, but used the 4 version a few times with good results, using TomTom, no issues with iPhone overheating, but I have seen it before.
They did mention in a email when i asked about charging that they are working a way to charge, few issues, 1) new connector is longer so made the phone case too big, 2) they looked at having the connector in the part of the case and chaarging through the bracket but there is supply issues getting the connector for such things. So hopefully they will come up with something but in mean time it is a good case.