I just spent a week in upper Wisconsin camping. I am a side sleeper and I ripped the zipper in my old bag in early March. During my research, I came to the conclusion that this would be a good bag for side sleepers. I was not disappointed. I am also a very cold sleeper. The temperature was in the low 40s at night. The bag is rated for 15 degrees and I was at the perfect sleeping temperature (for me) in just shorts. I could see myself being comfortable at lower temps while wearing more clothes, but I think I'd use my fleece liner in the low 20s and below.
I paired this bag with the Big Agnes Insulated Q-Core Sleeping Pad (wide, long). This bag REQUIRES A SLEEPING PAD as there is no insulation on the bottom of the bag to save weight. I can honestly say that I had a better sleep using this system than I get on my bed at home.
I will be camping at least once a month for the rest of the year and I am looking forward to how this bag will perform in the colder months.