Mine have been good. I bought 08 limited new. I currently have 155k miles on it and to date maintenance has been: brakes and rotors at 90k,water pump slow leak replaced at 95k, and side view mirror motor went out at 132k miles. Brakes lasted so long I replaced with OEM, pump was covered with extended warranty, mirror got off craigslist for $70. I will drive it until it's dead and replace with another Sequoia.
Downside is the limited aftermarket selections. I am currently waiting for Bilsteins to be in stock to replace the shocks with a little more travel and spacer in rear. Even less option if you go with the Platinum trim package. Tundra Solutions forum has plenty on them in the Sequoia section.