I almost live in this place. The main street, Pio Nono, just ahead of the Universidad de Chile Law School, is full with pubs and other places to sit and have a drink. If you like a more tourist oriented theme, Patio Bellavista is for you. If you preffer the local feeling, just skip it and go to one of the pubs, just watch out when going back, as the night goes on it could be a little risky.
If you preffer a mix of both, just take one of the perpendicular streets and in no time you'll find restaurants and pubs away from the mainstream noise, but none the less interesting and fun!

many differents social groups very european, a lot bars and dance clubs where they play very good house music.