I owned a 04' Frontier and traded in for the '05 2.5L/5-speed - well worth it. Bigger everything and still reliable, expect for some body squeaks. The truck never had any mentionable problems but routine main. & a battery (not counting two wrecks which it took like a champ) and it's still running and hauling 1,000 lbs. well. I think the interior design and ergonomics are great for a king cab, and the bold exterior design sets it apart from the wimpier Tacoma and domestics. Would like to see a more stroked 4 (or inline 5?) base model - the 2.5 L does great for the weight of this sturdy truck, but acceleration and torque are issues. I hope to get the 4.0 next time.
Comfort, styling, nice (but tight) manual transmission, not having to spend time at the dealership to fix little stupid stuff. Plenty of clearance for off road fun; decent mileage for its size (an advantage of the 2.5 L), well laid out engine compartment and controls.
As mentioned, one wonders why you'd keep a 4-cylinder, even this good one, in a truck this size. Strip down the SE 6 and sell it for less. I'm there. Tailgate is clunky and body integrity could be better. Suicide doors are a pain sometimes but you need them. Wide turning radius.