I've had a MacBook for sometime and I'm very much happy with it. I do everything on it, and the 13" is certainly manageable.. That said, when I bought it I had a powerhouse desktop and a 22" monitor and didn't plan on using my MB as my primary machine, and if I was buying today I'd go for the Pro.
15" would be a nice extra bit of breathing room and I do find the on-board graphics limiting. I'd like to be able to multitask a little more (play tiger woods '08) and I'm not so much a fan of the glossy screen.
But at the end of the day the MacBook is an excellent compromise, though we'll just have to see what's new next year.