My two friends and I had a great experience at Hostel Downtown. The employees working there were all friendly and helpful; we were served a light breakfast in the morning and our hosts helped us flag a taxi to the airport. The place was clean, the kitchen was a bit messy but 100% usable and the two bathrooms were comfortable and spacious. Admittedly the neighbourhood looked a bit run-down; I know nothing about Santiago so I can't say anything conclusive, only that my own personal experience was that I never felt unsafe.