This is my first MacBook Pro, and it's only two days old, but I know already it's the best computer I've ever owned in terms of combination of power, portability, aesthetics, and features.
I was able to run uTorrent, listen to music, run Windows in VMWare Fusion while talking to friends in iChat, and the computer (a Core i7 15" MBP) didn't even get warm. My old MacBook would have frozen due to that amount of workload.
Steam for Mac lets me play games again without needing to turn on my gaming PC (which is over 3 years old). The graphics on this machine are surprisingly good for what I've thrown at it, and again, it doesn't really ever break a sweat.
The keyboard is softer and feels much nicer than my old MacBooks, and the touchpad is by far the best one on the market.
I love this computer.