I have both and I use Poser 5 exclusively. I love being able to create as many different libraries and folders as I need to be able to find my stuff (when I can remember what folder I put it in). I have used the cloth room to resize clothes a few times but not for much else--yet. I occasionally play in the hair and face rooms but haven't spent enough time to learn them very well yet. The firefly renderer may be slower but the quality is unbelievable. You still have the option to use the old renderer. By the way, I pre-purchased my Poser5 upgrade and, although I'm not happy it's so cheap now, I do not feel cheated about the price I did pay.