I have loved this truck since I have owned it. I have added all sorts of extras like intake and exhaust work, so that is why some of my ratings are high. My only issue that I have had with this truck is the backseat. Once my daughter was born, trying to get a car seat in there safety has always been an issue. Nothing has ever gone wrong and only replaced things that I upgraded.
I like my truck. Pretty good gas mileage for a V-8 (about 18-21 city and 22-24 highway). Comfy ride. A few problems with the rear driveline. Had to replace both u-joints about 6 months ago and now it is squeaking and clanking again. Rear axle probably needs to be rebuilt. 3-rd door is nice, but back seat as a little smaller than I'd like. Pretty good power and towing capabilities. Heater is bad- not very warm and I have to put it on high to even feel any air flow.
I owned a 2000 GMC Sierra 1500 for 4 years. Although, I must say, the engine and trans were reliable, partly because I used Mobil 1 synth. oil and never beat on it. Other things with the truck started to fall apart, i.e., the ABS system would intermittently go off at less than 5mph on dry surfaces, the fuel gauge would start and stop working, the right side mirror was flopping around in the wind, the tailgate handle (plastic) broke off when opening the tailgate one day. The brakes were terrible - including the rotors and way too much distance was needed to stop. The driver's door lock got jammed and wouldn't lock no anymore. Power window linkage broke. Radio lights quit working. too much!