I had a '04 Sport V6 and my goal was to sell it before I hit any big repairs. In Oct of 2013, the head gasket failed, and that definitely counted as an expensive repair. Other than that, it was a very solid and reliable vehicle.
I now have a 2014 TEP, and I do enjoy it much more than the '04. With the '04, I couldn't get a moonroof because there wasn't enough headroom for me. The 5th gens have a higher roof, so I can fit in there fine with the moonroof. The combo of moonroof + rear window is sweet! Beyond that, I never really liked the seats on the '04 because I couldn't crank the front up to support my legs. I ended up putting a handful of washers between the front of the seat and the floor to prop them up a bit and this helped. The bolts are plenty long enough to accommodate this.
In addition to having leg support on the driver seat of my '14, I also really enjoy the softex seats and the seat warmers. Leather would also be nice, but I very much prefer the softex over cloth.
I'm also a huge fan of the sliding cargo tray. It's perfect for how I pack when going on camping trips. I think that those who don't like the cargo tray just don't know how to use it to its full potential. The rear bumper on the '14 seems like it sits out further than on my old '04, so you effectively have to reach over the bumper to access the cargo area. With the tray, you slide the gear toward you to reach it. This is especially important if you have a water container because you can just dispense water out of the back without worrying about spilling in the interior.
Though I really like the look of the black interior on my '14, it definitely shows rub marks on the plastic very easily. The gray interior of my '04 was never showed any problems. My solution was to create a simple metal rail that clamps onto the back and sides of the cargo tray. This prevents gear from touching the panels in the cargo area, and also allows me to have some simple tie downs to keep my gear from shifting while off road.
The '04 did feel a bit more peppy on the throttle, but I appreciate how the 5th gen drives. It seems to encourage you to drive with a lighter foot.
After 10 years of owning my old '04, I knew all the places where rocks would hit and ding up the paint, especially along the rocker trim and the rear fender. I noticed immediately that Toyota has a different choice of materials in these areas on the 5th gen. The rocker trim on the Trail is an unpainted plastic, and the lower portion of the rear fenders have a stick-on guard to protect against rock hits.
I recently put a new suspension in my '14 and new tires, so I can also appreciate that Toyota gave us room to put a 285 spare under the truck.
I have zero regrets for selling my '04. It was a good truck, but for me at least, the '14 is a much better vehicle.