I have been *almost* perfectly happy with this truck since day 1. I consider it a really sport oriented truck, compared to other brand's compacts. It drives just great and accelerates hard when you ask it to. I love everything about it, and after driving another vehicle, it's a pleasure to be back behind the wheel of this truck. In short I love it.
So why do I say "almost" perfectly happy? The fuel mileage leaves something to be desired. Every Frontier owner I have spoken to has the same complaint. I guess the pep in the 3.3 comes at the price of MPG. I have had GM V8 engines get better mileage, seriously.
With the 3.3V6 most people notice a ticking sound for a few seconds after a cold startup. I was told this is harmless, it's just slack in the hydraulic lifters as they come up to pressure. I was using 10W30 oil, and when I realized 5W30 is recommended I switched at the next oil change and all, but eliminated the startup ticking.
So in summary- mileage sucks, but this truck is such a great driver it just may be worth it. Be warned on the mileage though.
Other than that, until the rocker gaskets hardened and started seeping oil at 165,000 I didn't have one single mechanical problem. Nothing! What more can a guy ask for?