Friend ordered me the open back option in size 9 but my heel was popping out so I sized up to a 10 (being no half sizes). The shoe slips on well and feels great but wonder if having a half size would be better. The shoe opening was too loose so had to pull the laces tightly enough to tie the shoe. Once tighter, my heel stopped slipping out.
All in all, these are cute, stylish, and cozy but sizing up may be helpful.