It was fine, when I first slept in it I woke up a bit sweaty, but not too bad, just had my sleeping bag open and the mat tucked inside and after that I was pretty grand. I guess it depends on sleeping bag/clothing worn as well? Breathability didn't seem to be an issue for me.
How was the alpkit?
I slept in mine a few times, but always woke up sweaty as I found it didn't breathe at all.