Like the previous reviewer, I have knee problems (tendonitis) and wanted a nice pair of slippers that would be comfortable to wear -- and I love these so far!

I bought mine to wear inside the house only, but the nice, thick bottom on these would make them great to wear out of the house, too.  The inside is lined with the faux fur, and they are really comfy and soft -- and keep your feet really nice and toasty!

I've also noticed that these do help with posture.  When I wear them, I've noticed that I stand up straighter.  The bottoms are also quite thick, so they make you about an inch taller.

As for sizing, I'm a 7 1/2, but since these don't come in half-sizes, I bought an 8 and the 8's fit great with socks on.  (If I'm barefoot, though, they feel  bit loose, and I feel like I have to grip into the toe area a bit more with my toes.)  My feet fit perfectly inside and my heels don't hang out the back.  If you're between sizes, I'd also recommend going up the next size up since I know that the 7's would have been much too small on me.

I haven't had these long enough to see if they have true toning benefits, but I'll be sure to update my review after I've had these a bit longer.  My plan is to wear them around the house as much as possible so I can sneak in some extra toning!