I haven't seen a 17" mbp in person, but I just got my 17" 1.5 ghz powerbook delivered. Yeesh, this thing is biiiig. And this is only 1440x900 resolution too. I can't imagine the newer, higher resolution mbps. That's alot of space!
In addition to the firewire 800 and extra USB port compared to the 15" model, the 17" has less problems than the Fifteen incher's.
The only thing I am worried about the 17" is some people posted that it is easy for the screen to move around. I think this is because of the simple physics.
I have to say Apple did a great job for the 17" model's design as it does not look bigger than a 15" model. I was not able to tell the difference in size when I was at Apple stores between the two models (unles of course I cheated by looking at the tag).