They do keep coffee warmer a little longer & they're lighter weight than my other ceramic mugs.  But what I really like is that the outside of cup doesn't get hot so I don't burn my fingers holding it. I have little arthritis so if my fingers are aching I can put them thru the handle & wrap them around outside of mug. Plus it's just a good looking mug. I got the 15 oz for coffee (since I usually do 14oz) & the 10 oz  cup for tea ( I usually only do 8oz) I do hand wash them just to be on the safe side & so far no clouding issues like I've read on other reviews.  Glad I bought them.