I have no experience with it, but maybe this article would be helpful?
http://www.soundonsound.com/sos/aug03/a ... ueball.htm
Here's another set of reviews:
http://recordinghacks.com/reviews/tapeo ... icrophone/
Blue Microphones in general aren't a real popular brand. They do have a niche presence with some of their studio mics (the bottle series) but are now trying to get into a more consumer market.
I wouldn't mind trying one out sometime but the design of the ball alone gives me concern for use as a vocal mic since it has to be mounted directly to the mic stand (no clip) and therefore angle adjustment is limited to the capabilities of the stand and of course you can't take it off and hand-hold it. Seems the ball is still most popular for mic'ing instruments in studio situations.