Traded Mercedes C300 and a Ram 1500 Hemi, and traded both on the Sierra.
Mine is an SLE Doublecab with the All-Terrain package and 5.3 V8.
I've only had it for 1000 miles so can't really comment on reliability, but truck is very solid going down the road, whisper quiet, smooth, luxurious and just a joy to drive.
Its actually more comfortable than the 2011 Mercedes was.
The 8" touchscreen stereo with Bose speakers (not listed on sticker or GMC site for SLE, but came with my All-Terrain) sounds great, but the bluetooth and USB connections to my iPhone 5s are a bit flakey.
No NAV in my truck, but OnStar works well.
Drove 400 miles yesterday, heated bucket seats very comfortable.
Quality of interior fit and finish.
Outstanding sound insulation.
This is a big, 4-wheel-drive truck and the rear suspension isn't quite as smooth as on the 2012 Ram 1500 I traded, but its still a more comfortable truck to drive long distance.
Ride is luxury-car quiet and while you can feel pavement irregularities, it is very well damped and never jarring.
Double cab has flat load floor with seat folded up.
LOVE the heated bucket seats.
All-Terrain package on the SLE trim level has a durable cloth upholstery that breathes well, looks good and is quite comfortable.
My truck isn't even broken in yet, but I got 22 MPG over 200 miles at 75 MPH.
Steering wheel slightly off-center to driver seat.
Wasn't a big deal in the 1990s, just wrong in 2014.
No heated/cooled seat option in SLE model or even with cloth on SLT.
Doublecab slightly less roomy than Ram's Quadcab.
Touchscreen interface can lag and USB connection to iPhone flakey.
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