Seats wore very fast and have seam splits. They are the durable looking cloth type, but they aren't durable at all, and they are very uncomfortable, but that's always been an issue with Nissan P/U's.
Cheapo center console lid broke.
Cheapo A/C system has been troublesome since the truck was just a few years old. The lines used seem a lot flimsier than your average A/C lines, and burst in the Arizona heat, and it is a killer in a 120 degree summer. I am a mechanic and have seen all models of the Nissan lineup with early A/C issues.
I'm not a big fan of the newer Nissans.. the last one I had was an 84, and it had 300k on the original motor and was beat down from day one and still running.
I say the 3.3 non-supercharged V6 is a very good motor if you maintain it. One thing I do not like about the motor is it is belt driven, which means more work to do on the truck, but it's not that big of a deal, I just prefer a chain over a belt. The other thing is the gas mileage... gets around the same as a full sized 1/2 ton V8 truck.
Transmission has been flushed twice in its life, and has never given me any issues.
A/C system is the most troublesome part of the truck.
Interior quality is so-so, but it's a truck so it's acceptable. It just would be nice if the seats weren't wearing so badly; they started showing major wear at around 100k miles.
Body and frame are very solid on the Frontier, and for being a 2wd, this truck does great off-road due the the Desert Runner package. This is a great truck to take camping, or take to the desert or dunes with the dirtbikes in the bed.
It's a very reinforced. I've been rear-ended twice this year; once by a Kia Rio, and the Rio was badly damaged, and my rear bumper was slightly bent but barely noticeable (never fixed it), and then I was involved in another accident on the freeway, and was hit by a full-size truck and the bumper now looks like trash. They hit the quarter panel a bit, but with a new bumper you wouldn't notice.
As far as the quality of the metal and body of the truck, Nissan still has it! They don't call them hardbodies for nothing LOL. Both times I didn't pursue insurance or police due to the low amount of damage. I feel very safe driving it.
Gas mileage SUCKS. I average 17 mpg.
This will probably be my final Nissan however, they seem to be losing their touch each year. I like my German cars, but make considerations for trucks, and my next truck will probably be a Ford Ranger, Chevrolet Colorado or Toyota Tacoma.
But I have seen a few Frontier trucks, both 2.4 and 3.3, with 250-300k and still running in my career.
There's just something rubbing me the wrong way with this truck. I think it's mainly the gas mileage and the A/C.