We skied in Alagna a few years back on the basis that its supposed to be a freeride mecca.  It was good but the snow wasn't amazing when we were there plus the big main freeride lift was out of action.  Rumour had it that they were going to build a new gondola / cable car going miles up into the backcountry (with Monte Rosa in behind) so that it was a La Grave stylee "get out the lift and you're on your own" kinda place.  I've never heard whether they got round to building it yet but the terrain up the back there is amazing so in good snow it would defo be a cool place to ski.  The whole Aosta valley has pretty good skiing and you can get an Aosta valley pass (covering Courmayeur, La Thuile, Pila, Alagna, La Rosiere, Champoluc, Gressoney (maybe others I've forgotten about) - we've thought of doing a season with that pass before as on a good snow year you'd get some great skiing in with Chamonix etc just through the tunnel.

Haven't skied there but I've been up the valley (its full name is Alagna Val Sesia) and its a pretty impressive place.  Val Sesia is supposed to be a bit of a mecca for white water kayaking as well so sounds like a pretty cool part of the alps all in all!  I skied over to Cervinia (also in Aosta valley) from Zermatt a few years ago and to be honest wasn't that impressed...