I have a nearly 6 year old (very early build, custom order) 2005 Limited V6 4x2 w/ sunroof deletion, X-Reas, JBL and side airbags.
It currently has 56k miles.
Very early in its life it started having an issue with weak startup when it was cool outside and the engine wasn't warmed up already.
See the video I made to show the dealer here:
YouTube - Weak Toyota 4Runner startup
The dealer resolved this by replacing the fuel pump under warranty, but it took a LOT of complaining and some repeat visits before it got resolved. Frustrating.
Additional issues:
-Driver's side headlight has, in the last year or two, become heavily oxidated, despite the car being garaged at both home and work and having Plexus headlight cleaner/protectant applied 2-3 times a year. Passenger side headlight shows no hint of oxidation under identical conditions. I haven't fixed this yet.
-Dashboard developed a small crack on the passenger side top part of the dash roughly where I expect the airbag presses up against it from the inside. I didn't give it any time to see if it would spread, I took it to an interior repair specialist that screwed it up so badly that they had to pay to have my entire upper dash replaced at a cost of over a thousand bucks (to their insurance company). That was fun.
-Maybe it's just my perceptions have changed over time since I've moved from some sportier cars to some smoother cars (our 2nd vehicle), but the 4runner seems to drive more like a truck than it used to. The X-Reas suspension seems pretty stiff and bumpy on rougher roads. Stiffer than I remember it being when new.
-Dye has started to come off a tad on the driver's side left bolster despite being conditioned often.
-Dash lights have a very slight flicker to them when it's cold inside the cabin.
That's it, though. We're pretty happy. Basically except the weak startup issue, everything has been cosmetic or subjective in nature.
We plan to keep it until at least 100k miles and really if it's still reliable then I see no reason to get rid of it.