I seem to be able to do fine on both the "chiclet" keys on the current MB/MBP line, and the iBook/PowerBook G4 key style. I do have to say I prefer the way the iBook handles keyboards, though... (Not sure about the PowerBook, since I've actually never seen or used one in person, believe it or not.)
I've never had too much trouble adjusting to things like this, though. Now, if you wanted to get into trackpads... every Mac's throws me a bit off (being used to PC trackpads), though they seem like they'd be nice to adjust to.