It's one of the fastest drives out there witjhout a doubt and if speed is what you are after, then it may be the best choice. However, they are overpriced and the speed advantage they have over general 7200K drives is not something that a normal user would make advantage of. Many people use the Raptor for gaming or the OS to minimise loading times. I would rather invest into a nice large HDD with decent specs.
I've got one of the maxtor drives with a 16mb cache and it seems to do quite well, haven't benchmarked it against raptors, but empirically it does better than other 7200's