I'm loving it and surprisingly not missing a manual gear box at all. It's more comfortable over all the speed bumps and potholes in Reading compared to my IS220d Sport. It's quieter, there's more space for passengers and luggage, the Mark Levinson stereo with the MM option is awesome, and the extra 100hp means even thought it's bigger it's faster in a straight line. The handling is obviously not up to an IS and I've not really had a chance to throw it around too much yet but it's good enough to live with so far given the sort of driving I'm doing.
Things I don't like: the warning beep on the auto boot open/close, and I think I'd prefer reversing sensors instead of a camera as they give better detection at the corners. Fortunately someone had the optional front sensors fitted. These aren't as good as the factory fit ones on my IS as they give false beeps when raining etc but you can switch them off and they're better than not having any!
All in all I don't miss my IS at all, except for the keyless entry which is bizarely missing on the RX. The RX is faster, bigger, more comfortable, more practical and has at least as good economy compared to the Sport version of the 220.
At the moment I have a contract that I can walk to so the car is only being used for taxi service for my children, shopping etc so just short drives around town. I'm getting about 26-28mpg for those sort of journeys which is about the same as my IS220d. The hybrid seems to take a mile or so to warm up before I can get it running on electric only. Certain journeys on flat, clear roads I can do 3-4 miles almost entirely on electric so I think if I was driving it around town for longer journeys I'd see a better average. The little long distance driving I've done was mid-30s.