I've been using this bag as my summer sleeping bag. Contrary to another reviewer, I have not found it to be too hot and I am normally a sweaty sleeper. Its very light and packs down nice and small. It seems paper thin compared to how low rated it is. I can't vouch for this bag in low temps because I have a 0 degree bag that I use in the late fall/winter. Overall a good bag that I would recommend due to its light weight and packability.
I've used this primarily in AZ temps in hammocks during almost every season including winter. This bag held up very nicely and kept me very warm. The long version fits me perfectly as well(I'm 6ft). It also packs down very small which is amazing for my own personal needs. Just throw this bag and my hammock into the bottom of my pack and I'm ready to go anywhere!
It's warm enough for most outings, and has a double zipper allowing venting at the footbed. There's a small little pocket at the chest on the outside perfect for storing...things. I'm not sure what, I use it for my nightly lip balm. I wouldn't put my glasses in it though! Despite the good things, the zipper will catch on the interior mesh used to seal out air around the zipper. I had to cut mine off honestly, because I got locked inside the bag not once, not twice, three times! The bag is a little bit long and makes me sweat something fierce for an unknown reason. I'm cold going to bed, but in the middle of the night, I wake up soaking and HOT. I assume the bag doesn't breathe well.
I picked this up on sale because the 0 degree bag I've used for 10 years was used more as a ground pad or blanket than bag. It's a really nice temp but I haven't been in anything under 45. Also note this bag comes with a compression sack which saves you $20-30. In the compression sack it really compresses down to a small package. Granted its smaller fill makes that easier compared to a lower rated bag. I have been exceedingly pleased with this bag and highly recommend it.