they fit too tight.  i wear a 7.5 and got that size and it felt very snug.  no wriggle room whatsoever.  and i was wearing regular socks, not even  my exercising socks....i ended up selling them to my girlfriend who luckily did like them, she wears a 7.5 as well !  go figure.  i know that's not very helpful, maybe her feet are more narrow than mine.  i do need more space in the toe area usually and have been using the Ghost 4 and Ghost 3 line but decided to give these a try.  so glad my friend bought them off me because i passed the date i could return shoes by......and wished i had purchased at zappos where you have a year to return stuff.  definitely something i have to consider nowadays since i am bad at time management...:}