After reading the reviews on this shoe I bought a pair for my Zumba class.  I usually wear a 9 1/2, sometimes a 9.  I bought a 10.  They're tight.  My toes are smushed and the shoe toe is hard plastic so there is no wiggle room.  At the end of one 60 minute class I couldn't wait to get them off.
Also - these shoes are suppose to help make gliding easier.  That is an under-statement.  My Zumba class is on wood floors.  You will SLIDE all over the place in these.  They have plastic soles.  Hard plastic.  Stopping when you want is harder than you think.
All in all I'm not impressed with the shoe.  I plan on trying Puma - which all three Zumba instructors had.