Second GMC I owned and the "MO" is the same: Things started going wrong, repairs started to add up and had to sell the truck before something serious happened to it. Lots of electrical issues especially with climate control system. Stay away from any vehicle with the dual-zone HVAC. Some of these issues can only be solved via dealership who kills you on parts & labor. Traded it in for a more reliable "American" truck: Toyota Tundra. It is built in San Antonio, TX with American labor & parts. Mine was built in Mexico...go figure!
I have a GMC Sierra I bought second-hand with the optional GFX package. I really like the extra exterior/interior features such as two tone paint, stripe on the side, carbon fibre dash, white gauges etc. At first the 4WD did not work, however after a quick cleaning of the connection from the wire bundle to the solenoid on the side of the transfer case, I have had no problems. It came with the 5.3L aluminum block engine and pulls quite hard. Tow/Haul mode is great for uphill towing. The cab had an annoying grinding noise which was quickly remedied with some hockey tape on the cab door latches. Overall, a great work truck and daily driver.
Carbon fiber dash pannel, white gauges, a sharp looking truck. Comfortable on long drives, roomy enough for six 20 year old people to ride comfortably (perhaps a little cramped, ext. cab). Driving carefully, the truck computer shows I get 18 MPG combined. I calculated up to 25 highway, very reasonable for a 5.3L I thought. Warrenty is long gone, however lots of room under the hood makes oil/spark plug changes very easy (the reason I don't have a Ford).
Some things I thought could be better are the dash board design, though simple and trouble-free, it looks cheap and lacks innovation. Also I dont like the factory GM radio. This is an easy fix though - aftermarket deck.
I love the engineering, some of the design is lacking though. A problem GM should really adress.
Not a bad truck until the warranty was up. Before then, the only thing to go wrong was the rear door latch adjustment. It worked well in winter (western Canada), got great highway mileage and was reasonably comfortable. For the past two years the following have gone wrong: transmission replaced at 65K, 4WD position sensor replaced three times, tie rods twice, front hubs once. My mileage is 4/5 highway / 1/5 gravel. Its never been driven hard and has had very little mountain driving. Fit and finish are not great but not bad either. Accessories still all work. I bought the truck after having an Olds Alero and Saturn Ion (both had serious drive train issues). I won't buy anything from GM again.
Comfortable to ride in long distances. Great fuel economy with the 4.8. Some nice interior features. Nice looking exterior without all the over-the-top styling seen on 2005 era Fords and especially Dodges.
The great fuel mileage comes at a price. GM pushes the mileage numbers by programming the transmissions to shift to OD as much as possible which causes a lot of internal stress. Strong headwinds at 60 mph mean driving in 3rd! Weak transmissions and 4WD components just aren't up to the job.