I thought the N20 was laggy off the line and sluggish at low speeds. Once it's up to speed, it has nice power but for a 45-49K car well equipped, I expected better. The 335 satisfied those expectations and is what the 328 should be. Sorry, but the 328 isn't close in driving experience to a 335. It's a fine car if MPG's and price are a concern.
I don't think it has anything to do with the N20 being a 4 banger either. The Japanese have done some pretty amazing stuff with 4 bangers. Give BMW some time, they should be able to shore up the deficiencies of the N20.
Also, Those of you ragging on the N55, I can't tell if your underestimating it or overestimating the N54. I've driven both. Both are great engines, and I think saying the N54 is exponentially better then the N55 is an incorrect statement. I think N55 is strong, has a wide powerband, pulls fiercely in all gears, and has a great engine note when pushed. (At idle, it's unimpressive, though its nothing an AM exhaust can't help) This engine is highly underrated, and I am biased because I own one but that doesn't mean it's not true.
Current: 2010 E90 M3 - JBM PP,TP,ES,CW,Beast
Retired: 2012 F30 335i Sedan - Sport Line