I have had this e90/e60 vs. the older debate with family and friends quite often. I really dont believe that the e90 is a bad quality vehicle at all, just when placed next to the older (iron generation) BMW's, there is no contest. I still believe that a well serviced and maintained e32/e34/e36/e38/e39/e46 will outlast any later BMW, or any other late model car for that matter at higher mileages. The only thing is you will never be driving a new vehicle. Its a give and take situation.
The e90 has followed the route of many other vehicle manufacturers i.e trying to get the most out of a vehicle for the least expense possible, and it is starting to show. E90 6 cylinder oil usage, e90 323i camshaft wear, earlier e90 335i HPFP problems, 2007 e90 steering lock issues, e60 M5 oil level issues, etc, etc...
Later model BMW's are still definetely worth owning, just that after motorplan are on your own in relatively uncharted territory. I think that trying to compare reliabilty on a car that is 7 years old and has covered only 100 000+ km against cars that have proven their metal at well over 300 000 km and 15+ years of age (there are dozens of e36's, e32's, e34's, e39's and even a few e46's to back this up) is abit fruitless. Lets just wait for the e90's to prove thier high mileage and old age mettle before we can start defending their reliability. I think we can all agree that over engineering (something that BMW did oh so well) is almost dead.
Lets face it, all new car makers (and not just BMW) have followed this "disposable" trend. Damn sad, but its true.
@novio: I dont think that the e90 is as bad as stories make it out to be, its just that they seem to have quite a few more niggles than the previous generation, whether this is a case of theres just more to go wrong, or poor engineering is anybodies guess. If you dont have a motorplan then this could prove to be a costly excercise. I think that if you are going to own an e90, motorplan will be the ultimate piece of mind. If you feel that you really need a change of vehicle, and cant hold on to your legendary e36, then a 320i/325i/330i e46 F/L can only be the other choice. If your heart still wants an e90, then just try to get one that is as new as possible (later models generally have teething problems ironed out) and make sure it still has MP (to protect your bank balance)
I still regret selling my e36 328i to this day. I wish I never did. based on that, decide carefully....