Relatively accurate rating, comfortable, luxurious shell
The rating on this bag is fairly accurate, though I'd suggest wearing a layer or two if you're going to push it close to its rating. I've kept mine stored in its large storage sack, and still find it very warm. There is a review below mentioning that they've had some issues with storing it in its large storage sack has caused it to lose its warmth. So be aware of that. Granted, hanging a bag or laying it flat is a great way to store it, but not all of us have that kind of space available.
The shell/lining of this bag is luxurious and quite comfortable. Also, given the fact that this bag is synthetic, it packs down to a decent size and its weight is reasonable.
The Lamina 0 is a great snow camping bag, particularly if conditions are going to be a bit mixed, and consist of some wet snow or even some rain. Also, if you're car camping the larger size and weigh isn't going to be an issue.
If you're backpacking and out in these conditions I'd suggest throwing some more cash at a down bag with a GoreTex shell with a more realistic rating. However, given the price, as long as you factor in the size, weight, and slightly liberal rating of this bag, its a decent choice.