I've had my Macbook for about 2 years now. The fact that I haven't had a single problem with it that couldn't be resolved within 5 minutes sums my experience up very well.
I like the OS a lot more than Windows XP and 7. The iLife apps are great, especially Mail and iCal. I also like that there's a lot more open source and free software available for OS X.
Physically, the keyboard is great, and has made any other keyboard I've had to use feel really uncomfortable.
The screen is perfectly sized – big enough to have enough room for everything but not too big to take away from it's portability. It's very light and slim, and the battery is amazing. It hasn't failed me at home or on the go.
I like the disc drive and how it loads (by sliding the disc in rather than having to take a whole tray out to put the disc on). The built-in webcam is great, and although I always think I don't need one, I find myself using it all the time. It's really great for recording music and working with video. It's an amazing laptop all around, and I couldn't live without it!