These are pretty nice mitts -- very warm, seam taped and nice construction. I haven't had them too long, but they seem built to last too.
A couple of complaints: they don't provide much dexterity (even for mitts, which I don't expect to have much). This was especially the case with the included liner, but I had better luck using thinner liner gloves (which is nice with these -- you can use any kind of liner you want). But with the included liners I could barely do anything with them on! The other thing is that this might improve as they break in and the materials get softer and more flexible with time.
My other major complaint is that the gauntlet part of the mitt is a bit small and it was quite difficult to stuff the cuff of my bulky winter jacket into the glove for a good seal. This is especially hard because once one glove is on, it is nearly impossible to adjust the second one due to the reduced dexterity! A low bulk jacket will be fine, but not for a heavy insulated parka (which is generally what you'd be wearing if you've got these mitts on!)

Bonus: warm as hell and well made

These were my first "hard core" mittens. i bought them two years ago and returned them two years ago. Backcountry sent me a replacement which was also defective. Do not buy these mittens they have terrible dextarity and warmth. Not taped seams. Don't buy spend a little more and get a better mitten. Back country did rectify the situation so they get a big thumbs up, the product however, big thumbs down.

These things are toasty. I went up the hill on a rare sub zero day and found them so warm I actually had to take them off a few times to cool off. They're really thick but if you're on your snowboard it won't bother you at all. I would say they're perfect if the material/leather on the palm were a bit thicker or more durable. I'd buy them again without hesitation given the price/warmth.

Just a note that the 'product specs' on the side of this page show that this mitt has a nose wipe. This is not true. The Cornice mitt has NO nose wipe. I even chatted with the online help that pops up on this site to ask if the mitt had a nose wipe. The customer service rep said there was- but nope, no wipe!
The mitt is built very solidly just as every other OR product I own. They make good stuff and stand behind it! Can't wait to put this mitt to the test!

I have had these mitts for years and they will probably serve me for many more. They are so burly and will stand up to any kind of abuse. I use them with the PL 400 liners and they are extremely warm.

I echo the others reviews about the dexterity. It's a little difficult to grab smaller things, but I guess thats the price you pay for really warm mitts.

I finally got to use my new Cornice Mittens this weekend. I was on a solo Snowshoe backpack up in the Rattlesnake Wilderness of Northwest Montana. After pushing up hill over a eight-hour day this old man was not only beat but getting cold. As I pulled out the Cornice Mittens and slipped them on I notice that they appeared well made and the fact that I was able to handle gear was also a big plus. Well in no time at all my hands were warming up. One less thing to worry about and I was able to get camp set up with no more worries about cold hands. Good gear to say the least

I have been looking for a few years now for some mittens to replace my beat to hell Burtons from 1998... these are perfect. They are simple, solidly built, and warm. Removable liner so you can use them on baltic days and not so baltic days, throw a small glove liner in there if that's your style... just a very nice, simple, strong mitt that was exactly what I was looking for.

The best thing about these mitts are that they are built to last. For the past several years, I've blown through one or two pairs of gloves/mitts each winter. I needed something that wouldn't fall apart with intensive use (I work outdoors daily in winter, plus recreating).

As for the dexterity comments others have raised, the loss of dexterity is a small price to pay for warm fingers. I keep a pair of winter work gloves (actually, OR's Extravert gloves) handy for a quick swap if I'm going to be doing anything needing nimble fingers.

These mitts are perfect for snowboarding, too.

I wear these shells snowboarding with either a fleece mitt or a liner glove (or both) and it is the perfect set up. I do take them off to do anything more involved than just strap in or out. The cords make taking the shells off and on quick and easy. They fit easily over my jacket cuffs. They're waterproof, windproof, durable (no wear signs after 2 yrs of carrying sharp snowboards around) and I'd buy them again in a heartbeat if I lost mine.

just too small if you have big forearms. gauntlets are so much shorter then older models. sent back but they are made bomb proof

I agonized over the decision about what gloves to wear on a multi-day alpine hike/climb. I finally dropped the big bucks on these bad boys, and I was NOT disappointed. First, I should say that I tend to have cold fingers/toes at altitude and I brought extra chemical handwarmers just in case. With these mitts, I didn't need them. They are very solid and durable, and I loves the gore-tex waterproofing. The insulation is wonderful and lightweight. They are certainly big mitts, and dexterity is a problem. I also agree that the gauntlet is a little bit too small and can be a pain. These negatives aside, I am very glad that I paid the extra bucks and got these mitts. I still have all 21 of my important digits.

My hands are perpetually cold and I am constantly on a quest for a warm functional mitten. I think I'm getting closer! These mittens kept my hands pretty warm in cold,windy weather. I won't lie and say they're perfect...I still use hand warmers when it's really cold out, but these did the job much better than many mittens I've had in the past. I won't drop them while fumbling with my camera or phone because of the "idiot cord" and the nose wipe definitely comes in handy. I do wish they had a little goggle wipe though.