Good, but not brilliant.
I've used Bell helmets for a while now, as I was originally a Giro dude and then they started completely f***ing up their retention systems, so I gave up Giro and went to Bell, as everything they made seemed to fit me perfectly.
I love the new Sweep, but if I have to be completely honest, I have to admit it doesn't fit my head as well as my previous Bell (not sure of model name). It doesn't seem to be as "deep", so it doesn't come far enough down the front or the back of my head - it just feels like it's sitting slightly too high.
It's not severe enough that I don't still have time to appreciate how comfortable and well-ventilated it is, but it's always hard to forgive something expensive that doesn't fit as well as its older, poorer and uglier cousin.
(Might explain my taste in women... ) However, Lord Nikon just bought one after having similar trouble with other helmets his whole life and reckons it fits him like a glove
(the helmet, not my woman ).
I love Specialized bikes and their gear and when it's my annual "let's buy a new helmet for no good reason" moment, I'll be heading in that direction. In the meantime, though, I'm 90% happy that I'm wearing a really good helmet with the Sweep.