I honestly love my 4th gen and V8, its got 103k on it and runs like a champ, hell in january I did a recovery in the snow for two members with a 3rd gen & 2nd gen daisy chained to my rear hitch and yanked them both in one shot no problem. Engine's been running happily with no issues and just finished pushing it from Bay Area to San Diego in under 6 hours over the Grapevine with barely a whimper or a flicker of the temp gauge.
Toyota built the 2UZ-FE series SPECIFICALLY for low range RPM and truck use in their Land Cruisers, Sequoias, and Tundras; so you take care of them and they'll be as bulletproof as the ol' 3.4L!
I like the the 5th gen exterior styling, but the interior is not as comfortable as my 4th and the lack of the 1UR-FE (4.6L V8) drove me away from them.