I have loaded it down with 3+ tons of tile and it handled as if nothing was in it. It has been on various trip which required 4X4, with a quick turn of the nob I was climbing a muddy hill or going through sand. Size does matter, the room in the back fits 3 full sized adults (6' plus) and they had plenty of leg room, without touching the front seats.
The roomy interior is everything you would associate mega cab to. And the storage in this truck is amazing.
The front cup holder does not really allow for anyone to sit in the middle.