Super smooth ride. Lots of power and torque with the trusty 4.9 L.
I've only got 31,000 miles, but it has needed nothing except a radio fix due to a faulty circuit board. There are stories on this Forum of cars like mine getting 150,000 miles with no problems other than routine maintenance. There is one with 279,000 miles from this forum and the 4.9 was still running strong when I last talked to him!
If these cars are maintained and cared for they shouldn't be much of a risk if you pick up an older one.
Things to watch for might be the air shocks in rear, and make sure the coolant was changed often along with the supplemental GM pellets/tablets.