I've skied Las Leñas, Catedral, and Penetentes on the road to Chile from Mendoza just before the Paso Christo. I liked Las Leñas the best of those three but the others are definitely not "bad."
If you ski off-piste there are some killer runs on the back-side of Penetentes that you can hike to, as well as some couloirs west from Manzano, Mendoza towards Chile. You'll want a guide for that trip. Just be aware that if you go off-piste here and get in trouble there isn't much of an organized rescue operation. They pretty much write you off unless the TV cameras are there, and they'll make it look like they are doing a lot work.
That being said I've telemarked couloirs here that had my adrenaline running for days afterward. The Argentine ski guides are some of the best skiers I've ever been with.
Hope this helps.