I love, love, love my Emus! I got them for Christmas and haven't taken them off during the day since!
I wear a 9 1/2 or 10 shoe. I received a 10 and they are a bit too big. I'm sliding in them just a little bit. So, I would say they run true to size to a little big. If you wear a 10 1/2, I think the 10 should be fine.
I might have to order another pair for $50!!!