So, I'd like so start by apologizing for this review being so much longer than most,
but I really want to give as much information as I can for anyone who may be unsure about buying.
I've been wearing these for around two weeks now and washed them twice, and these are my thoughts.

First off, the fit and design:
I do have to say that this is my first pair of boxer-brief style underwear,
so I'm not used to this type of fit, however previous pairs of underwear typically don't quite fit right,
particularly being too tight on my legs while fitting fine around my waist.
So bear those two things in mind when I say that I think they fit quite well;
they have a good amount of stretch throughout;
the elastic of the waistband has a great amount of stretch, but never feels too tight or too loose;
the legs fit well; they are overall longer than I'm used to, but again, I'm new to this style of underwear;
and overall they fit snugly but are not at all tight.
So, overall, I have no complaints: 5/5

Next, the fabric:
This is my first experience with Yak fiber and I have to say: I'm immediately a fan.
I think the best term to describe the feel of the fabric would be "nice:" it's soft and smooth,
and overall just really nice feeling.
And that's when I actually notice it: most of the time it's so comfortable I don't even notice it anymore.
This is particularly noticeable (or, not noticeable?) when I'm in the heat - which, where I live, is often over 100F:
the cotton I usually wear quickly becomes damp and it doesn't breath and it's just uncomfortable and I notice;
whereas this fabric does become a bit damp, but it breathes so well I never really notice it,
to the point where I almost wouldn't say it's a comfortable fabric, because I simply don't notice it.
One thing that's worth mentioning is that when I first started wearing it,
there was a period of a few days where it felt a bit itchy, but it quickly went away as I got used to the new fabric.
I think this sort of thing can happen whenever you start wearing a new type of fiber as your body gets used to it.
I can't say anything yet about how warm it is, because it hasn't been cold here yet,
but I think it's safe to assume that it is warm based on the other reviews.
(if this website lets me edit this review, I will give some more definitive information once it gets proper cold here)
The only real complaint I have is with the Merino: someone I know is allergic to lanolin -
as well as wool generally, I believe - so unfortunately I can't give her anything with wool.
Because of this, I would love to see a version of this Yushu collection with the Merino replaced with Alpaca or Bison,
so that it is entirely hypoallergenic.
For those of us without wool allergy issues though: 5/5

Now durability and longevity:
I currently have no real way of knowing how long they will last,
but I will say that the fact that they can go much longer without being washed,
combined with the durability of wool - which I believe to be greater than cotton -
should mean that they will last significantly longer then ordinary cotton underwear.
I guess we'll just have to wait and see, but assuming the above is correct: 5/5

Lastly, the price:
Are these worth paying 50$ for?
Yes, I think so.
Even without considering the benefits I listed above, the fact that they can go so long without being washed
means I think they're worth at least 7 pairs of cotton underwear each.
Then you do factor in all the above and I think they're actually a very fair deal.
If I knew for certain that they would last at least twice as long as cotton,
then I would say this is an incredible deal in the long run, but even if they last just as long, I'd say they're worth it.
So overall for the price: 5/5

One final thing I think is worth mentioning:
If you usually wear anything that doesn't breathe like wool does and you get these,
be prepared to feel increasingly unsatisfied with your other clothes as you wear these.
For me, it seems that the longer I wear them, the more they highlight how uncomfortable things like
cotton and polyester can be.

Overall though, my only complaints are what I said above about the Merino,
and the fact that I'd like to see a few more color options.
But these don't warrant the loss of any stars, so I'll say 5/5 from me.

Great fit. Will be buying more.

Can't get my hubby out of these! Nuff said!

Warm and comfy

Go to underwear!!! Awesome!