Sure I can compare it to the e46. The dealer was nice enough to give me a '05 325 Auto as a loaner before mine got here.
First off let me say that the '06 has a lot more power, even when I test drove the 06' 325 I felt it lacked a little power.
The six speed manual is a really nice transmission, but because the torque, did not go up as much as the HP, you end up downshifting more than you might like too. I previously has a TDi Golf, in that car you could almost drive off in 5th gear. In the 330, 6th is only good for cruising at over 80mph, there is very little acceleration.
As for the twisties, this car is a dream. The sport package keeps the car planted like nothing I have ever driven. It holds, and holds, and holds, I keep my foot down, and the car keeps turning. I have not gotten anywhere near losing it.
Inside the car feels even nicer than the 5 series. Things like the AUX port in the center console are a great touch, and if you don't have a MP3 player, you can just pop in a CD with MP3s on it.
The best possible praise I can give this car, it is worth every penny.