I can't really think of anything, to be honest. But I don't really have high expectations, either. It's a really nice truck, and are there things I would change? Probably, but I don't know that calling it a "disappointment" would be the right word. Things I would probably change/improve/alter:
1. Shifter knob. I've come too close to grabbing it when I wanted to turn the radio up several times. I appreciate the extra space but still think I'd probably prefer a console shift lever.
2. Tow mirrors - these are kind of ugly and should be available as power folding and body-color or chrome. The tow mirrors on my Titan were far better looking and superior functioning to these unless I flip them up, which makes them REALLY ugly
3. A little bit of road noise when the back seats are folded up. Don't notice it with them down so I assume part of it is just resonance in the big empty chanber behind the driver/passenger seat.
4. Back seat back doesn't fold down and give you room to put tools and stuff. This was my favorite storage spot on my Titan.
5. The passenger seat doesn't go back far enough. I know that eventually my wife will scratch the **** out of the glove box door with her handbag and stuff because the space is small.
6. I believe my back sliding window rattles if it's open all the way. I'm not 100% sure because I don't really care enough to investigate that hard.
So those are the things I can think of. Nothing that to me qualifies as a disappointment. I love the truck overall and would still buy it even knowing these things.