Mate of mine just got one, threw me the keys.
Quiet. Eerily quiet, just tyre noise unless you've got the throttle nailed, then you get a decent V6 growl. Completely silent at parking speeds on motor only.
Fast. Official 0-62 of 5.9 seems a bit understated and doesn't give a clue to the power delivery, which is seamless (as you'd expect with a CVT and an electric motor) and relentless. Overtaking is brilliant, no lag, no waiting for kickdown, just power. Had me grinning every time something in front of me rapidly became something behind me..
Dull. No wood, metal or leather on the dahs, very "toyota" inside and out. Lots of gimmickry, brilliant reverse camera, electric memory everything but just no character.
I drove it about 10 miles on back roads, then about 8 miles on dual, drove it very hard and got 31mpg. Bearing in mind that's what i'd get out of the E class driven like that, and that it's faster, quieter and petrol (so fuel is cheaper) it's a compelling package let down by not looking like anything special.