I wrote a long rant before, and I used it for a little while, so I figure I would make some more points and give it a review. Mostly I think they should not have wasted so much time on 'whiz bang' features like coverflow, and emulating the finder sidebar, and spent more time on making it truly be a finder replacement. I know this would end up being a hack, but, I would love to be able to never open finder again, and have PF totally replace it. The checkbox to make it the default browser (which was in 4.x) works for the most part, but some apps insist on calling finder directly, and it subsequently opens finder. PF also had a hard time integrating with automator. There are tons of these little features that would make the most 'hardcore' of users happy, yet they tried to focus more on these dumb features that make nice bullet points, but are not very useful.
As it stands, I can't recommend the 5.x branch for any power users, and I am happier with the old 4.x.