Good, works well. This is what they give us at work. I used to have the 17 inch version, but it didn't seem very practical: hard to open on a plane, bulkier, and at work I use large monitor anyway. So I exchanged it for this one. It is fairly stable (I still use Tiger), since it has a built in dual DVI, it can work with my 30 inch monitor at work, which is also very nice. As far as I can remember, on Dell laptops ddvi was not even an option. 4 GB RAM option is also very handy.
Downsides: runs hot sometimes, so I had to install this fan control to manually up the rpms of the fan; batteries go bad often, and they are expensive; I use Eclipse as my dev environment and it is SLOW comparing to Ubuntu Gutsy, which I run at home.

If you are looking for a nice laptop bag, I really recommend this "incase" backpack, it is really nice (but overpriced like everything at Apple store)