I have owned the car for just a few months now. However, I have put almost 10k miles on it. The car was repossessed, so I was a little worried about prior maintenance performed such as oil changes, etc. But, I took the risk and bought the car. I also own a 1986 Nissan 300ZX which is an awesome machine. Very reliable for a 20 year old car. And for those of you who do not know, Infiniti is the luxury division of Nissan. Don't believe me? Pop the hood and look at a part, it will will say Nissan (or another Japanese brand, depending on the part).
The powertrain in the car is outstanding! The motor actually made the 10 best list! 230hp and 26+ mpg! However this car DOES need PREMIUM FUEL. But, that roughly equates to $1.50 more each fillup compared to regular octane, so no big deal. At 105K miles, the spark plugs should be replaced. It uses platinum tipped ones which are a bit pricey at $9.50 each, but they last a lot longer than conventional spark plugs. The dealer quoted me $300.00 for the job. However, this task is listed under the "Do It Yourself" section of the Owner's Manual. So, I went and purchased the spark plugs and used the spark plug wrench that came with my 300ZX (from the factory) and did the job. It took less than an hour of my time, and I saved $240.00. The transmission is smooth and responsive, although at certain speeds when downshifting could be beneficial it sometimes doesn't. Also, in the morning, the transmission will not shift into overdrive for a few miles. This is not a problem. It's designed to do this, allowing the transmission temperature to be warm to prevent damage.
The quality is typical Nissan, very high. Interior is very nice. Rear sunshade is very useful for preventing sun from damaging rear leather seats. Automatic climate control is very useful, allowing driver to "Set it and Forget it". Bose stereo sounds good even when the subwoofer isn't working.
Overall, a great car. I highly recommend any V6 Nissan product. My experiences with the VG30E (300ZX) and the VQ30DE (I30) have been outstanding. I have never understood why Nissan is never mentioned in terms of reliability like Honda and Toyota. My Nissan experiences and everyone I know who has owned one will tell you that they are awesome. My 1986 300ZX has 153k miles. No leaks, drips, smoke, or oil consumption. Go Nissan!