Directions weren't easy, because of no street names. So exit the U of C exit for the norte exit of O'Higginns, turn right, and the first street you come to has no sign. Turn right-- that's Lastarria. It'll curve around, keep going, and just past a bunch of restaurants, is the street.
Most places in Santiago don't have heat or insulation nor hot water in the sinks, so just be ready.
When I got off at the metro stop, I looked around and thought, hmmm. This may not work. But as soon as you get off of O'Higgins, it's fine.
The hostel is very clean, tidy, nicely done. Breakfast is typical, but close to plenty of places. The wifi works great, too. It's not a party hostel, but people who stayed seemed perfectly nice. Really recommend it, especially if you're older and want a good atmosphere. I stayed here while trying to find a job and an apartment.