The back of the shoe was rubbing against the heel and causing blisters. I had no socks, which probably contributed to the problem. I've only worn it once. I hope if I break them "in socks" they will get better.
Pros
These were a bit big for me. But they look great, are very comfortable and are a great price.
Cons
The shoes are not waterproof, making them unsuitable for use in wet or wet conditions.