To each their own of course.
To me, the E just looks both more boring/conservative, and over designed/fussy. The 5 just seems more youthful/elegant/COHESIVE (not odd), and even bold.
I've seen lots of 212's on the road, and although the front is quite imposing, the rear is one of the most boring on the road, and the side profile is just too boxy and the car literally looks like a wedge. It's got an aerodynamic, and relatively swept back shape (albeit upright and formal), but the lines and styling ruin it to me.
The 5 might be more simple, but as in all forms of art, simplicity reigns supreme in many ways, just because the E is more complex and challinging to look at, doesn't make it better necessarily. Problem with cars today, is they're getting so quirky, people feel it needs to be controversial to be good. I find the E to have too many flaws to me personally, to consider it an ace design all around. The 5 I don't find any real flaws on, save for the front end perhaps, which isn't its strongest angle, however it in no way IMO is the fail that the E's rear is.
Interior wise, I don't like the cold and box style the E goes for. Reminds me of what I didn't like about the E60, with some "80's Benz" throwback vibe, the 5's shows better so far, pic wise at least. Materials wise we'll see, like I've said already of course, the 212's plastic and over-use of it kind of upset me, so I'm crossing my fingers the Bimmer will prevail.