Got a medium and they fit tighter than I normally wear my mittens but the tight fit really does keep your hands warmer. These come with mitten inserts which were awesome because companies always make inserts in a glove style. I like the mitten inserts because they keep my fingers together and warm, unlike gloves. I took these out to Colorado over break and I didn't even need to wear the inserts with these mitts because they are nice and warm on their own. But I did use the mitten inserts in a pair of warn out airblaster mitts that I like too much to not wear, even thought they're on the cold side b/c they're 2 years old.
I got these at a good price, so worth it. I only wish they had gore-tex technology in them b/c then they would be invincible. I'm not sure if it was the snow or my hands sweating but they did get a tad damp inside after a day hiking the park in CO (but not enough bother me so I'm thinking it was sweat).