As someone who owned a '12 E92 M3 with Competition package + ordered a F30h w/M-sport (delivery in 5 weeks), I can offer you probably the most unique perspective. Not sure of anyone else going from E9x to F30?
You can substitute my experience with the E92 for the E90 you're considering, as they drive/perform virtually identically.
The M3 is raw and often noisy, but in a good way. The rawness is personal preference, some people may not be used to it. The two main knocks against the M3:
- It drinks gas like nobody's business. At 14mpg, it will dent your wallet quickly. Some people will tell you they get 16mpg, and that might be true. But you'll want to drive it to get the most excitement, and that means <15mpg, which is almost comically embarrassing for something that is not a 1-ton dually.
- The tech is outdated, compared to a F30. Sure, the Navigation is similar, but the F30 gets a much nicer instrument panel, and you get HUD. If you enjoy tech, the F30 feels about 10 years newer than the M3.
An F30 335i is a wonderful car.
You must get the dynamic handling package. Skip the 20" wheels IMO. Unless you plan on tracking the car, the F30 with DHP is plenty sporty for around-town driving. The torque is quite nice! The M3 does not feel short on torque, until you drive around from 30mph->60mph in a 335i. It feels pretty effortless with the F30, the M3 needs to get wound up a bit more.
What you're really missing on the F30 is of course the S65 motor. A true masterpiece! But you pay dearly in gas, and often the lack of opportunity to get it above 5000rpm during normal driving.
For me, it boiled down to recently needing the addition of 2 more doors, and the frustration with the lack of mpg in the M3. I have a heavy-traffic commute. I'm expecting my ActiveHybrid 3 to offer 40mpg, more torque than the M3, and tech that is substantially better (AH3 has the next-gen BMW Navigation).
Do I miss my M3? Sure. But it can't do everything quite as well as the F30 can, for my needs and situation.