First things first, I love the shoes.  They fit me perfectly and I think the purple ones are "cool" enough to wear with normal clothes.  When my feet are measured I wear a women's 12 narrow or about a 10.5 in men's.  A Brooks 11 fits me very well in this shoe as well as the Beasts I had once upon a time.  I don't have a TON of room but I wouldn't consider going bigger.  If you have a wide foot you might want to consider going a half size larger than your usual athletic shoe or possibly this just isn't the shoe for you.
It's really important to note this shoe is not cushioned and if you're looking for a light shoe with any give at all I might suggest Saucony's Kinvara, which I also liked running in a lot and is also very light.  The Brooks sole just feels like hard foam when you squeeze it.  Right now I use this shoe to walk around in (I walk between 3 and 5 miles every day) and at the gym, but when I start running outside again in spring, I might prefer a different shoe that makes me feel more bouncy.
Again, I can't say enough how much I like wearing this shoe, but I guess with the hard sole they just feel like incredibly comfortable well fitting street shoes, and when I put them on they don't mentally trigger me into running mode.  I'll try them in spring and perhaps report back, if this version of the shoe is even on sale.
++Update
I have started jogging in these on the treadmill. Not a ton, maybe 4 times a week for 3 or 4 miles?  But I still love them and I'm buying another pair.