If there is one thing I can say about this truck, It's reliable. As of today my Silverado has 320K miles, I have had to replaced the front hubs, wheel bearings, and the water pump, and of course the brakes. I had problems with the climate control selectors.. While running the AC there would be a thump and the left side would instantly go to full heat.. And the fan control module melted once, lots of smoke.. The truck still runs pretty strong, but wear to the engine and trans has begun to have an effect on performance.. but she's never left me on the side of the road, and the four wheel drive is still functioning normally. All in all, a very good truck, and if it died today, I couldn't complain.
Recently bought my 2005 ext-cab Z71 silverado 1500 a few months ago, used with 90,000 miles on it. I'm the second owner. Good things: Engine is still very quiet and runs smooth for having 90K on it, great on gas, ride is smooth, 4wd still works, interior in great shape, no electrical or steering problems. Overall still a great truck inside and out. Bad things: Doors rattle a little when driving over rough bumps, transmission shifts hard into 3rd gear and makes a "smack" sound. A/C makes weird gurgle sounds after I turn it off.
I had a problem with an coolant leak shortly after I got the truck. Dealership found a cut hose and replaced it. Had a condensation/fogging problem because a "gate" wasn't opening. That took longer, but we found the problem and fixed it. Truck is straight forward and functional. I would have loved standard transmission. Chose this over Nissan, Toyota, Ford, and Dodge.
I purchased an '05 4x4, extended cab, WT, in April. I think it's a great truck. I was impressed by the standard features (e.g. dual climate control, 4 wheel ABS, etc..) It rides great on the highway...I drove it from NY to the Rocky Mountains and was never uncomforable at all...that's a lot of driving. The engine is impressive (about 300hp). It's got plenty of power and has been getting decent gas mileage (for a truck).