I own a Titan XD Diesel Platinum Reserve, and have helped tow several 8,300 lbs TT's for a local RV company for a camper show. I can tell you that the XD was built for towing, especially in the 7000-11000 lbs range, way better than any other 1/2 ton. This was the reason I bought one, because they are far more stable at towing than any other 1/2 ton I've driven. It has a lot of the components of a 3/4 ton, without the high numbers and price tag. I can tell you that Hammster easily spent $55k on his truck or more if new (I know because my dad owns one). I only paid $42k plus TTT, which came out to be $45k OTD (brand new) with a 5 year/100K bumper to bumper warranty. As far as my towing experience, I pulled a brand new Sportstrek 372VIK, a new Cougar (forgot model) and a Keystone Bullet, which were all around 32-37 feet, weighing at 7200-8400 lbs. Pulled it like it wasn't even there. Stock tow mirrors also come in handy. The XD has a feature where you can check all the lights after you've hooked the trailer up by using your key fob, which is nice if you don't have someone with you. My average MPG's during the tows were average at 11. My daily driving MPG's are around 17-19, depending on traffic. The best I've seem was 21.8 MPG which was all interstate. It isn't the greatest, but it isn't bad either!
As for the negatives, which all truck brands have, I only had a few since I've owned it. I am one of the many who has the alignment issue that pulls to the right. I've had them try to fix it 3 times, the last time was an improvement, but still not fully fixed. It seems that every XD had the tailgate not work properly when purchased, but that was an easy fix from the dealership. You can get the exhaust smells in the cab during Regens, however, if you put the A/C controls on recirculate, it fixes the problem (obviously not the long term solution). They do have a small fix for it, but some complain it still smells. I don't notice it as I leave mine on recirculate. I also get the occasional "hard shifts" when upshifting from 1-2 and 2-3, but I've gotten used to it. They came out with a TCM and ECM flash to help fix the shifting issues. I personally don't consider any of these "biggies" because Nissan is addressing the issues. As for the XD being a first year model, of coarse it has some bugs/fixes that are still being worked out, but the truck is awesome. It rides really nice, feels luxurious, has a lot of the top end accessories, tows excellent, and the price was great for the capabilities of the truck. Obviously, it isn't a 3/4 ton truck, but is definitely better than the 1/2 ton trucks, IMO. It truly is a 5/8 truck, which is exactly what I was looking for. Hope this helps answer any questions you had.