This is my first MacBook Pro. I upgraded from a 13" MacBook, mostly for the larger screen, louder speakers, and dedicated graphics. I didn't like having two computers (my MacBook and an iMac), so thought I would simplify by using only one computer (my MacBook Pro). I really like the 9 hour battery life, and the larger screen lived up to my expectations, but it is a little bulky. It's also a little louder than I would have preferred (both the HDD and the fans).
The new 11" MacBook Air is tempting, though, so maybe one day I'll revert back to using two computers. But the MacBook Air's battery life will have to double in the meantime.