I have both. The Pro is worth the extra money as an all around desktop replacement type laptop. I like that the speakers are better, the graphics card is powerful, hooking up to a 30 inch screen, Firewire 800 is very fast and I depend on it for making FW800 to FW800 backups. I like the LED display and the keyboard is much better than any keyboard I have ever used. And you can pick your display if you didn't want to have glossy. (I don't mind glossy though.). Keyboard lights are cool and the standard 15 inch display is the perfect size to do real work and not weight much more than the Macbook.
The Macbook is almost as fast and more portable and I like the latch better. It feels more durable to me. It makes a better portable for my needs and I use it for Handbrake tasks when I have it at home to free up my Macbook Pro for gaming. I think it is a much better value than the iBook in it's day because it doesn't feel crippled with a slow processor, memory, or hard drive. And it is very easy to upgrade the hard drive on your own. It is the Macbook Air to me. I don't even feel it in my backpack and it doesn't take a lot of room.
If I had to be stuck with a single laptop, I would go with the Pro because it is seems to do everything in one package as a Mac with few tradeoffs. It cost more which is the biggest tradeoff. In 3 or 4 years, the Macbook will probably still not exceed the Pro on some of those features.