Having been a past Bimmer owner (last two cars before the Zed) I can say they are great all round cars and as you would expect quality engineering, comfort, safety, reliability and cost can be fairly ok if you need work doing, especially if you go to independent specialists, although saying that BMW stealers have dropped their prices so they they're semi-reasonable now. BUT......why change!!!! Zeds turn heads Bimmers are fodder!
In my opinion though if you're gonna look a BM, try out the 135 M-Sport coupe, I took one out for spin when I was looking for an upgrade.
I compared it with drives I took in the new M3 and 335 and to be honest the 135 blew me away. It's comparable in performance to the 335, with the bi-turbo it goes like whatsit of a shovel. It can also be used as a practical every day family car as it's a four seater and has decent boot space. Of course it doesn't quite match up to the M3 but it's close second. Even Clarkson loved the 135, said it's the best car they make and he's not exactly a BMW fan.
That said the Zed beats them all hands down........it's a love thing despite all the niggles you just can't a Zed outta the system!