I had an 06 Tundra Crew Cab 4wd SR5 with aftermarket leather. Leased it new for 3 years. Replaced it with a 3/4 ton truck and didn't look back.
The 1st gen Tundra was a light half ton for towing or hauling any weight. If you only need the bed to haul light stuff, it's fine. I'd you plan on towing a 6,000 lb trailer, it stinks. The VVTi and 5 speed trans were nice, but not an enormous improvement from the 2001 Sequoia we came out of. Nether towed our 5500# travel trailer that well. (upgraded to a much bigger trailer and thus the 3/4 ton truck now). The added HP made no noticable difference, it was the trans that helped a bit with the 2nd/3rd gear spacing for towing.
The Tundra does not have the same build quality that the 100 has. I remember brand new, complaining that some of the oval switches 4WD/Hazard/Rear Bed Light) on the dash didn't match.......one was off-black, the others were gloss black. No MPG readout, which my Sequoia had. Not sure of the condition of both rigs, but my new Tundra was nothing utterly spectacular. My 2005 lx470 is certainly much nicer and better built (this is comparing my then-new Tundra to my current 111k LX470). The double cab tundra is also a bit awkward, both in visible proportion and huuuuge turning radius, lousy visibility, etc. MPG was nothing spectacular, I remember high-ish teens on hwy (17-18?) which is nothing vastly superior to my Hundy. Driver's seat was a PITA to get adjusted to a moderately comfortable position.
I had problems with front suspension on my Tundra (TSB or recall, I can't remember which, something to do with an assembly-line defect), tensioner pulley squealing that took them 2x to fix, and a couple of strange drivetrain noises the dealer never sorted out before I turned it in (obnoxious creak every time you put it in gear). I bought the 3/4 ton to replace it about 6 months before the lease ran out. The Tundra sat in the driveway, undriven, for the last 6 months before I washed it and turned it in. I knew I had unused miles on it but didn't care enough to drive it. I don't miss it. Fwiw we enjoyed the Sequoia a whole lot more as it was proportioned a whole lot better and was much easier for my wife to drive and park.
You need to drive that DC for a weekend before you decide to give your Hundy up, for sure.
Ymmv, perhaps that helps a bit.