I installed Win7 Ultimate 64-bit on my MBP 15" i5 with no issues. It took a little bit to find the settings for the trackpad, but other than that all my device drivers worked just fine right out of the gate. I connect to a Dell ultrasharp 2001 monitor that has a usb hub with some other devices (external hd, etc) that all work. The only hiccup I haven't figured out in that setup is I can't setup my external monitor to extend my desktop to the left of my MBP monitor, it seems to only want to extend to the right.
I do Sony Vegas 64-bit video editing in my bootcamp'ed Win7, that's pretty much it. Everything else I use OSX.
I've only been running this setup for about a week but I am about 85% happy with the process.
The cons I have noticed...
Screen brightness on the MBP under windows seems to default back to the highest setting in the bootcamp control panel after a reboot, and it doesn't seem to use the light sensor to dim it automatically. Both those add to eating the battery faster.
Missing keys are a little annoying (ins/del/home/end) but I can live without them.
When using the bluetooth magic mouse the right click is much more sensitive in win7, I have to make sure I don't have any other contact with the top of the mouse when I go to click on the right side, otherwise it just does a left click. Again only a minor annoyance IMO.
I haven't done a battery drain comparison since I'm usually only using Win7/Vegas when I'm plugged in.
Performance I would say is right on par with a comparable PC laptop. You have to compare apples to apples here (no pun intended really

I have a desktop PC that is pretty close spec wise, the only difference is I have installed Win7 Professional 32-bit on it. Both my desktop PC and my MBP w/bootcamp run pretty similar performance, the scale tips a little to the MBP but I have to contribute that to the higher specs. I also have a thinkpad t61p running WinXP but that's not really comparing apples to apples so of course the MBP is much faster.
In my honest opinion if you want to run Win7 as your primary OS most of the time it seems a little bit expensive to opt for an apple device as your hardware platform of choice (laptop or desktop).
edit: you can always dual boot/virtualize OSX on your PC but that is soo much more of a headache it isn't even funny. i.e. My desktop PC is tri-booted for WinXP, Win7, OSX (not vanilla). Booting the desktop PC in OSX native is a huge undertaking and not recommended for the faint of heart. My thinkpad T61p I dual-boot WinXP and OSX. I also have vmware under WinXP running OSX SL vanilla.
moral of the story... getting a pc to run mac osx is possible, but is an absolute joke compared to bootcamp.