Have a '17 TRD OR. I like the ride, is smooth, feels good, fairly quiet. My overall mileage is 21mpg, but my daily commute has a lot of 35-55mph in it. The best highway mileage I've had was 23.3 but that was also going down in elevation half of that tank and with a tailwind half that tank. Overall average tanks on a road trip have been 21.5ish around 70mph.
This truck is certainly not without fault. The lower control arms whistle or humm at highway speeds due to all the holes in them. They now have plugs to go in those holes for that reason, or you can just tape them up. The front windows, at certain angles, also make a whistling type noise and Toyota has replaced a lot of window seals. The transmission is already on its second TSB update to get rid of shifting problems (like not being able to decide what damn gear it wants to be in - 3rd to 4th back to 3rd, 4th, 3rd, etc). Some people have also experienced a flare when shifting, of up to 400rpm. And many are finding low transmission fluid. I've read of a few issues where you step on the gas, and it just doesn't go - but only a few.
My truck has the occasional whistling from the window seals, it had the whistling from the LCAs before I taped them up, it was nearly a quart low on transmission fluid (which got me a free 6 year 100,000 bumper to bumper warranty from Toyota). Once I was accelerating from a light and it acted like the gas was cut off, losing all momentum, then started going again. Not a traction issue, wasn't spinning the wheels, just kind of fell on its face. But that was only once.
My biggest complaint about the 3.5 is the lack of bottom end power. My old 4.0 was much better down low in RPMs and going without having to rev it up. This 3.5 sucks unless you rev it up, but it does have more top end power.
Overall I do like the truck. Comfy, smooth, relatively quiet, just wish it had more bottom end power. And there is supposed to be another TSB for the transmission coming out in the next couple months.
