General
The closest ski hills to Santiago are the inter-linked resorts of Valle Nevado, El Colorado and La Parva. The road and lifts give great access to some decent alpine terrain. When the snow is right it is definitely an area worth visiting.
Snow
The snow is equal to anything in the world in quality, but unfortunately the quantity can vary widely from season to season. Safer to visit in late winter/early spring as early season coverage can be poor. The sun can badly affect storm snow so to get the famous Andean champagne you have to be quick!
Weather
Generally good. Long spells of fine weather with the occasional dump. Unusual to have long periods of low cloud and poor visibility. Perfect ski touring weather most of the time.
Terrain
Classic alpine. No tree skiing, just alpine bowls, chutes and faces. Short to medium length runs of 300-800 vertical metres. Some challenging stuff but in general it is wide open intermediate to advanced sort of terrain.