I recently upgraded the wheels and suspension on my 2008 E90 and thought I might share the experience since this forum helped me a lot. I drive 12 miles a day and so handling opinions come from taking on-ramps quickly and turning really fast at certain corners when its deserted.
First, the look is incredible. I feel like I have a new car. Going from 18" 219's to 359's with spacers and the B&G spring drop (from EAS and installed at Euro Auto spot in SD) makes the car look like an angry bulldog but in an elegant way. The drop is as low as I'd want to go. I feel like I have a new car (for only about $2k after I sell my old rims).
Comfort wise it is still better than my old 2006 330 E90 with those damn run-flats. It is less mushy than the 18"'s with stock springs and on sport mode on EDC it feels fantastic (not jarring, just feel the road in an intimate way).
Handlingwise the car now has much better feedback and steering feel and it feels much more planted. On a certain stretch of deserted road where I can easily hit 3 digits it feels like a bullet train whereas previously it felt a little top-heavy and not as stable. Taking corners is an incredible difference - I can take them 30-40% faster and it feels like its on rails. In comparison the traction control would chime in sooner before.
So thats my 2 cents. If you are a daily driver like me and contemplating lowering with spacers, DO IT. You can put EDC on comfort mode to carry passengers and then turn on sport for yourself. It is probably one of the biggest bang for the buck mods you can do. I feel giddy again when approaching the car like I did when I first got it
Merry Christmas and Happy New Year to everyone!
p.s. if you need mint 18"'s at a good price, see my ad:
http://www.m3post.com/forums/showthread.php?t=626365