I hear the terrain in Andorra is excellent. I think the reason it flies under the radar is because the storms & snowpack their aren't as consistent as the French, Swiss, Austrian & Italian alps.
If you are lucky & time is right, then it can be awesome. If you are mainly interested in terrain parks then, if they have some, then you are good to go and will enjoy being someplace off the beaten path.
Check out some links:
http://www.telegraph.co.uk/travel/snowandski/andorra
http://www.onthesnow.co.uk/andorra/reviews.html