The drinking experience is due to the somewhat wide margin also unusual at first, but even that goes after the 2nd sip.
Toll is the insulating effect. I have a normal and one of the double wall glasses with the same amount of 11 ° C cold water filled and let stand at room temperature. After 15 minutes the glass was normal at 13.5 ° C, the double was 11.4 ° C.
The 350ml version is now my favorite beer glass.