I think those Blizzaks you are talking about are the LM-18's. I cannot recommend that set of Blizzaks to BMW owners. They are the absolute best in the snow because of a very aggressive snow-oriented tread design and a special Blizzak compound, but there are so many drawbacks to these tires:
They don't handle well in the dry, and they are terrible in the wet. Since the tread is heavily geared towards snow driving, driving with these tires in the dry wear the tires down REAL fast. Also, when approximately 50% of the tread is gone, the special Blizzak compound is gone too, in which case they perform like your average snow tire for the remaining 50% of the tread.
This model Blizzaks are more suitable for people who live in Alaska or very far upstate NY or Vermont, or basically a place where it consistently snows several times a week during the winter. For most people, the LM-22's are a much better choice as they offer great dry and wet road handling, they last longer, and they are designed for sporty RWD cars.