I bought the XPS M1210 for a single reason- the size. When I bought the XPS M1210, it was the only laptop easily available on the market that had a discrete video card that was also under 14 inches. This 12 inch machine does require an upgrade to get that video card, but it makes all the difference in the world. I have 1GB of ram installed on it, and it has been upgraded to have an nVidia GeForce Go 7400.
With this machine, I am able to play relatively new games, and still carry it to and from class with no strain on my back. I see other students with 17 inch monsters that they carry with them, and I wonder how they support that size! While they wrestle with their laptop and try to find an outlet to plug their computers into, I get around 5 hours of non-gaming use with my extended battery. And for gaming, I can play 2 solid hours of Oblivion on a full charge. Find me a 17 inch machine that can do that.
The XPS M1210 is made to be a solid performer in a tiny package, and it performs that job beautifully. People still give me comments about how small my laptop is, and every time I tell them how much it can do, they look dissatisfied with their own.
Bottom line- The M1210 is not a desktop replacement, but it doesn't claim to be. If you want a laptop because of its ease of portability though, you have just found your new computer.