I really like these short slip-in boots. I normally wear an 8 1/2 so I tried an 8 and a 9 and while they both fit, I ultimately chose the 9 because the 8 was just a little tight in the toe box but the 9 fit great right away with no breaking in required where the 8 would've needed some stretching. I have a regular medium width foot for reference, so it's possible a more narrow foot could go the other way. Also, since I'm in between sizes I almost always go to the next size up so, if you're in between sizes, I'd say just do what you usually do.
These boots are very comfortable, warm, and feel supportive. The faux fur doesn't make my feet feel too hot or sweaty. Plus you can wear thin or thick socks as these shoes easily accommodate either. They also have just a little height to them so the bottoms of jeans or pants won't get wet from rain puddles, snow, or slush. I'm really looking forward to wearing these as the weather cools off!