In reply to Phillip Benson:
There's two large campsites in El Chalten, adjacent to one another, which are mainly full of trekkers (like myself), however there are a number of climbers. I stayed at the one closest to town, however I heard the one behind it has more climbers. The countless hotels/hostels are rather pricey peak season (Jan-Mar), as the climbing/trekking season is so short, so camping is the cheaper option for long-term.
Be aware the weather is absolutely dire. The Atlantic, Pacific and Antarctic weather systems all meet in Patagonia, so expect, rain, hail, sleet, rain, sun, more rain, a glimpse of sun, then snow, with intermittent 40 mph gusts that will blow tents into the trees! The winds are insane. Bring a sturdy tent, guy-lines and plenty pegs. I chatted to countless climbers who had been there for months and barely got anything done, besides sport in the valley. When a weather window appears you see them all marching up super-speed to get stuff done! So use the non-climbable days to keep fit doing the endless treks to Cerro Torre, Fitz Roy, Laguna de los Tres, etc. Plus take a few days to El Calafate to see the spectacular Perito Moreno Glacier!
Other advice is take a rock-solid suitcase with rugged locks, as there's endless baggage handling gangs at BA airport who will steal your kit. They arrested a gang, but it continues. Even pay to shrink wrap it at the UK departure airport. Bring spares of any kit you may break, as kit in El Chalten is like Snell Sports in Chamonix prices on steroids! Enjoy! It's a truly spectacular place!