Funny that this thread came up... my brother just picked up a 08 350Z Enthu model for 25.5k which was several hundred dollars below invoice....
We bought the car in New Years day and I actually have been driving the car for the past week (My BMW has stayed in the garage since its been raining and i hate washing my car).
My 2 cents.
BMW 335i is a "sporty car". It has a sporty feel to it. the 350z is a SPORTS car. It definitely feels like a sports car. Its a two seater. I personally love that part (Im 22, i dont care for back seats..my brother who is 18 will not have much use for the backseat either).
The 350z has a stiffer clutch with a short shifter. I prefer the gearbox on the Z over the 335.
I was surprised that first gear goes up to 50MPH and second gear to 70MPH on the Z.
I like the setup on the reverse on the Z alot better than the 335. You have to Push down, and move it to right to be engaged in reverse.
350Z has crap interior material. But i dont expect a luxury interior for a car we paid 25.5k for. Still, the car has a fairly nice layout with timing clock, over-revving warning, etc.
I guess i always liked the design of the 350Z. Its a hate or love it design. If the E92 never came out, I wouldnt have bought the bimmer. I really cant stand the design of the E90.
The 350Z with the revised VQ engine gets 13.5-13.7 on the quarter mile from what I have been seeing. Quarter mile, its a drivers race between the 335i and 350z in favor of the 335i. But in the tracks, I think the 350Z will kill it.
350Z also comes with LSD on all their models (except base) and brembo brakes in some of their models.
All in all, it all comes to how much you are willing to spend. If you can only spend 25-27k range, the Z is definitely a great car. 350Z is not a luxury car, thats where the G37 comes in. I personally would not want to drive longer than an hour in a 350Z where as in my Bimmer I can drive it from San Jose to Sacramento without wearing myself out.It's also rumored that the 370Z is comming out next year which will likely be 330hp and 200 pounds lighter.