NickM wrote a review of Black Diamond Prime Alpine Touring Boot - Men's on February 26, 2014
Familiarity: I've put it through the wringer
Like many folks, these were my first touring boots; my first ski boots actually.
Pros: They're comfy, wide, fairly light, and tour well. If you have super wide feet, these may do well for you. If you can find them on a great deal, a great 1st boot for sure; well, maybe for a few months...
Cons: Downhill performance leaves a lot to be desired, so I was forced to upgrade within 3 months of owning these. They're so high volume and flexible that downhill can get a little rowdy, and I'm a pretty damn intermediate skier. Also, the liner is a lightweight, flimsy piece of garbage. Some aftermarket liners would really help this boot, but you'll end up spending as much as a 10x better boot.
Bottom line: They work, sure, but there are a ton of better options that tour well and ski significantly better . Black Diamond is definitely quite a few years behind the curve on ski boots. I have friends with Quadrants, as well, who aren't exactly in love. After using something like Scarpa's Maestrale or Freedom, BD boots are kind of a joke.