...know more about this car? let me know if they really have problems?

The only concerns I've seen are the drivers seat slider assy fails to move the seat forward and backwards, and the front compression arms make a squeaking noise and need new bushings.
These are both warranty covered and no cost to the customer.
The G35's and M35's are nice rides and the AWD versions are even sweeter.
Do your maintenance and Infiniti will take care of you.
They are a pleasure to drive.

http://www1.epinions.com/pr-Cars-2005_Infiniti_G35