If you're already a merino lover, here's your review: Buy this!
This is my first Buff, but I'm familiar with them from camping/rock climbing guys I know. I was sold by the addition of merino, which is a wonder fabric for the outdoors. It really does all the things it claims, isn't itch, and just. won't. stink. I live in Florida, so something that can keep the sun off me without stinking by the end of the day (looking at you, synthetics) is great.
The merino Buff is longer than a regular buff, but still piles comfortably on the neck as a gaiter. It's a great length to cover my neck in the sun, and makes some other really useful shapes. The tying directions that come with it are good, and Buff's website has a video on tying as well - don't worry, easy stuff. I got the Colombo Cru design, which looks pretty great in person.
Minus 1 star as it's a little thicker wool than I was hoping. I don't see an official fabric weight for it on Amazon or Buff's page, but it feels like a 200 or 300 weight wool (again, just my estimate). This is a little heavier than what I wanted it for - again, I live in Florida, so I prefer lightweight or ultraweight wools. I see for another reviewer, it wasn't heavy enough - so, think about what you'll be using it for to decide. However, merino is very breathable so this still works well for me.
Bottom line: Great product, if they come out with a microweight merino option I'll buy that.