We were very happy to have selected Erratic Rock 2, but it might not be the best place to stay without wheels of some kind (we were on bicycles). While we were trekking in Torres del Paine, the owners stored our bikes and extra luggage, despite the fact that we stayed with them just one night. The welcome was warm, the rooms very clean and attractively albeit sparely furnished, and the breakfast was hearty. We enjoyed the chance to chat with other travelers and also with the owners. Although the hotel is out of town, there is the advantage of its quiet locale, especially since Puerto Natales is not very attractive as a town (excluding the area next to the water!).

Erratic Rock 2 is located in a private home about six blocks from the center of the city. Very clean rooms on the back of the house. Spartan furnishings but staying in a home allowed us to meet folks at breakfast and in the late afternoon. Great owner (has studied in the US and is currently a teacher) with helpful connections all over town.
Met a family from Holland taking the year to travel around South America as well as a couple from Australia. Recommended to us by a Swiss couple; for about fifty US dollars, it was a welcome change from hotel routines.

excellent little bed&breakfast, owned by the same people as erratic rock hostel a few blocks away. intended for couples, so each room has a double bed and clean private bath. this is not a fancy b&b but very clean - perfect if you're on a budget and just need a sleeping spot before or after visiting torres del paine. marcela manages this inn and she is super-helpful and knowledgeable about the town and the park-- there's even homemade bread at breakfast every morning! she spent time as a student in the states, so no worries if you don't spanish.

We stayed at Erratic Rock II (sister hostel to Erratic Rock) in Puerto Natales. ER II is for couples whereas ER is backpacker.
The family who ran ER II were friendly - even got to practice my spanish. There is luggage store to store bags whilst trekking in Paine and the rooms are chalet style - ensuite double rooms. The room was clean and comfortable inc breakfast.
You can contact ERII through www.erraticrock.com.
As we had limited time we booked our trip to Paine in advance - I would recommend Path@gone agency - www.pathagone.com as they were brilliant in sorting out our accommodation and activities in the national park. we did the w trek - 2nd day horseriding. The French Valley is well worth the detour up - it's amazing in good weather!