I went from a Black MacBook (i.e., 13") to a 1440x900 15" MBP last summer. I love the horsepower, screen size, and some of the "luxuries" (i.e., optical drive, FW800 port, ethernet, etc). I don't know how relevant this is, but I'll also point out that I almost always have it plugged into an external monitor when I'm at home (currently a 27" Apple Cinema Display).
HOWEVER, I'm a student, and I'm rarely on campus (every weekday, at least 4 hrs/day) without my MBP in my backpack. It's heavy, and it doesn't help that it sits in a Tom Bihn brain cell (heavy duty case, but big/heavy) inside my backpack. Despite this, I've pretty much gotten used to it, and I really like my MBP.
After yesterday's refresh of the MBA and ACD, I'm thinking the combination of those two devices might be awesome:
- The 13" MBA has the same resolution as the standard 15" MBP (1440x900)
- Do I really need to mention the size/weight (or lack thereof)?
- SSD = very snappy
- With the latest ACD refresh, the ACD features 3 USB, FW800, AND Ethernet. One cable to use these (thunderbolt).
tl;dr: I got used to my MBP and really like it; however, depending on your usage, you may be better off with a newly refreshed 13" MacBook Air + 27" Apple Cinema Display.