Generally the pre-LCI X5s seem to be terrible in terms of issues. The LCI is pretty solid. 07-08 E70s were terrible I've had my car for almost 20 months now. Zero issues, except needing a new oil level sensor. That's it. I've tried all the German brands and except Mercedes (never again), I've never run into a POS car.
That being said, there are still tons of issues with the 35i. HPFP, injectors, etc. not solid at all. The diesel seems to be the most sorted of the bunch.
Comparing luxury SUVs, in general, of course, the German brands are going to be ranked lower. Lots of things can go wrong with them. What's interesting is that in the most recent JDPOWER, Mercedes was ranked higher than Acura, Honda, Hyundai. Crazy.
I guess German car owners do put up with some "issues" to have a better driving car. You couldn't pay me to go buy an Infiniti or Acura. BMW/Audi/Mercedes/Lexus. I'll do it all day long.