I used it for 5 nights in temps ranging from 0F to -15F. Plenty warm. I did use 2 mats (foam on the floor, xlite in the bag).
The no insulation on the bottom totally makes sense as compressed down doesn't do anything for you.
Only gripe is closing the zipper from inside.. gets snagged alot...
This review was written in the old system and had content requirements that are different than reviews written today.