My third Tundra (2001 SR5, 2005 SR5 4WD Crew). The motor simply rocks, its quiet, smooth and incredibly powerful. I tow a 5000 lb boat and you don't even know its there. The tranny works well while towing, but has trouble finding gears at slower speeds when not towing, especially when taking off from a light. Other than that, its my least favorite Tundra. It just doesn't feel well put together, the throttle is very punchy, I have several rattles and have had to replace the radio, oh and the little gas pedal recall. I commute and can routinely get 19 mpg if I use cruise control, which is awesome.
The motor, easy as that. Fuel mileage very respectable if you are light on your foot. Towing ability.
Squeaks, rattles, radio issues and recalls. Tranny could use some tweaking to cure some quirks.