These were great. I first got these to spend the summer in the Qatari desert, and they were awesome. I also had a pair of underarmor, and the icebreaker far exceeded them in performance. This goes for the tshirts also!
"Comfortable fabric, not a comfortable fit."
The fabric that these shorts are made out feels fantastic on your skin and is super quick drying, but the legs are too short and so it ends up riding up and you and you might as well be wearing tighty-whities after about 15 minutes. I don't recommend them as a good pair of boxers for casual use or as a more active undergarment.
A lot of friends would probably stare in disbelief if I told them my lightest, most breatheable pair of boxers were wool. Having just weighed everything to pack for my vacation, these are the absolute lightest pair I own, and will serve well to keep the sweat (and stink!) from building up. Look and feel great, soft and form-fitting.