i actually find the styling to be reminiscent of GM's own escalade.
the ford look-alike debate can be shot down by looking at the general bodylines of the truck. ford's have always had a curved bodyline with the front of the truck being lower the the back. you can see this in nearly any ford truck throughout time.
the lines on the gm vehicles has always been straighter, something more like a gentle slope than an increasing one. this design isnt a copy of ford's it seems to me that GM took their most appealing truck (the escalade series) and applied the frontal styling to the new generation of trucks. add that with the very large-flat surface of the doors that has been all the rage with automakers now (think TSX here) and you'll come out with this.