When it comes to the intended use of these gloves, they are fantastic. The windbreaker mitten works really well, and they are warm without being overly bulky. Every time a blizzard hit the northeast US this winter, I was out running wearing these and my fingers stayed toasty the whole time. If I started to get a little warm, I would take off the mitten part for a few minutes to let my hands cool down. My only complaint is about the fit of the gloves, which is really bizarre. I do not have small hands, and I have quite long fingers. However, the first pair of these gloves that I had were a size medium, which is what I usually wear, and the pointer finger and thumb were SO long that I could completely fold them over down to my first knuckle. So I exchanged them for a small, and the thumb is still about a quarter inch too long! The rest of the glove fits snugly, so going down yet another size isn't an option. If you have really long thumbs, these will be perfect. If you have average or short thumbs, these gloves will not fit properly.
*Update after the Antarctic Ice Marathon: Wore these with a thin glove liner underneath and my hands were warm and toasty the entire race. Being able to flip off the wind mitten for some temperature control was great.