Firewire 800
I carry these portable Firewire hard drives, and they are very useful when needing to service the Mac, and the file transfers are faster than USB 2.
Upgradability, Storage, ODD
I use this computer as my primary computer, and so it will need to last me a couple years. The MBPs hold up better than the Air, even my old multi-body Pro still worked just as well as the first day I got it, until I sold the thing.
Storage is important because I store A LOT of files, for clients, and the ODD is important as I also burn files into discs for clients. (Believe it or not, discs are still cheaper than buying each client flash drives!).
Planning on upgrading the hard drive to a 750GB soon, but right now the 320 is holding up a lot better than the 160 I had in my old MacBook.
Edge to edge glass
Come on, who doesn't like this? (Except for the people who don't like glossy screens
Power
It is more powerful than the MBA, and has all the power I need to do some work at the collaborative office, at home, and at school (when I go back to school).
My MacBook Pro suits my needs perfectly, and I do not need it to be thin as the Air, and I don't need the power of the 15" or 17" versions.