The Bandershobbs are new to D&D, I believe, as I think Drammatex (who posted right above you) created them for his home campaign and got them into the book.
I picked up MM3 yesterday, and I've been very impressed with the monsters I've seen so far. The damage boosts really make sense to me, and the new stat block seems easy to run. I'm going to be using exclusively MM3 monsters in my next session on Tuesday, so we'll see how that goes over!
My favorite so far? The Banderhobbs. I never used them in previous editions, but I'm going to have to find a way to throw them into my campaign.