Based on the reviews on Crocs.com (too small, too narrow) I ordered a size up. I normally wear a 10 so I ordered an 11. The 11 was too big. I think the problem people are having is that this isn't a traditional croc. It's more like a dansko or a merrell slip on. If you have wide feet, these are not for you.
I sent the 11s back and ordered the 10 and they are so comfortable. I do have a SOMEWHAT narrow foot but not overly so. I am going to order the brown ones next. These would be great for work where you cannot wear standard croc clogs but need something a little dressier.