I’ve had 2 UX250h’s over the last few months, whilst our GSF and RX450h were being serviced. I agree on the ‘go kart’ feel but found them much more responsive and faster than the ES300h F Sport i’ve had as a loan car in the past. Nothing against the ES, it’s a very nice car, but I was left disappointed with its lack of urgency. I guess it a great cruiser.
I came to the same conclusion as @rayaans regarding the ES compared to the RX, although ours is a 3RX.