When did you try it?
MediaPortal v1 is final and 1.0.1 is on it's way fairly soon (only 7 issues in Mantis still to be resolved).
I've used it on and off for a long time now, and yes it was very buggy at times, but now, with a nice skin (StreamedMP is my currect favourite) it is a very slick setup.
One massive benefit over WMC, if you have a house, is it's client/server nature. You can have a large TVServer box tucked away out of site with all your storage and tuners, then small, quiet/silent clients connected to TVs to actualy play back content.
edit as always with these projects, if you have problems, report them. Bugs won't get fixed as if by magic is no-one reports them for the developers. If the devs were having these problems, they would get fixed
