I agree that the G35 doesn't live up to its specs. I had an '03 6MT coupe that felt underpowered for having 280hp, plowed into corners, and was heavily lacking in refinement. The drivetrain suffered from NVH issues, convincing me that the VQ engine was best left to Pathfinders. I remember idling in drive through lanes or in narrow garages, and hearing all kinds of ticking and popping coming from the engine compartment. The shifter needed a lot of effort and didn't like to be rushed, and the clutch had a finnicky engagement point. It had a lot of promise as a fast, luxurious GT for under $40K, but it was neither comfortable or fun to drive.
The interior quality and assembly were questionable at best. Mine had 0.5" gaps between the rear quarter windows and panels. I bought the car new and babied it, but the faux-metal trim looked beat up and scratched after two years. Oh, and rattles galore. The '05 facelift included better interior materials, but it was like adding lipstick to a pig.