if you think that ip5 is too thin and small.. just add a bumper casing to it
anyway for serious matters, 4s and 5 don't really have a significant difference, other than the 16:9 4" display. overall the processor improved a little, battery life more or less the same (some cases 4s better), so think about it.
if you really hate ip5 that much, wait until 5s come out lorh