I got to use an newer MBP for a few days about two weeks ago.
Nice machine, cannot really tell much differance size wise between an older 15" PB.

But, the unit was very very fast indeed! Everything seem very speedy, much more so than the older PB's. I was comparing it to my new 20" intelimac, which is very speedy, everything is just snappy, apps open fast, internet was very fast, native applications were very fast indeed. Things like photoshop were not BAD, as slow as before on PB's. Photoshop was usable. MacOffice was fine, it took a few more seconds to open, but everything was fine when opened, including scrolling.

As for the wifi performance, this is an ISSUE with the macbookpros, RANGE may have been an issue in the past with PB's, I had a fine one that worked well. The CURRENT issue I believe is with a software driver for the airportexpress card that is in the unit. I would imagine that is being worked on and it will be fixed in the next software release.

I was getting about 3:00 hours, maybe 3:20 using wifi, screen at 80% and surfing, running DVDS, etc.

The final comment, is HEAT! The heat coming off the bottom is more than any other laptop that I have ever used. I could not keep the thing on my lap for more than a few minutes. It is NOT a laptop in that sense. I don't really know what is producing SO much heat, but buyer beware.