I have an X5 SD which I have owned for two months and 2000 miles now. I haven't owned an X5 before so can't comment on the ride versus the E53, I previously had an E60 535d. I think the ride on my E70 is superior to my E60 which I think shows how far BMW have moved the game on though I do think when there are any particualrly bad bumps/speed bumps it really rocks the car around. I would be empted to investigate suspension mods to rectify this but only after I have fitted regular tyres (see below)

Following on from what StumpyPete said about the runflats and not being able to repair them (most garages wont because the side wall reinforcement may not last if you get a second puncture as it has a limited life). I will almost definitely change to regular tyres when the time comes and carry an emergency inflation/repair kit for the severe blow outs. Most punctures are of the slow variety so it will still be possible to get home with normal tyres and then get the puncture repaired. As discussed many times there is no doubt the ride on RFT's is inferior to regualr tyres.

My view on faults is that I am far more about how they are handled than if I get them. I accept that I'm buying a highly complex machine and it can have faults. My comfort access failed 2 days after getting the car but my sales guy had my car colleted within 2 hours a replacement car left and the X5 returned 48 hours later. The problem was a faulty aerial.

I have a faulty temeprature gauge which I need to book the car in for and I have also experinced today a problem with the auto tailgate not closing.I can close it manually but it won't power shut...checked the lower door is shit properly so the car will need to go in.

My E60 suffered from a couple of small faults over the first few thousand miles...I honestly think with the complexity of these cars now it's almost to be expected to have minor faults initially.

Overall I am extremely happy with the car and I would say it's the best non M BMW I have owned. My previous nominee for that was an E36 328i Sport I had...it was a phenominal car in it's day and better than the E36 M3 Evo that replaced it.