I really like the tuner on my 2011.
I love using cruise control and was tired of the downshifting every time I could see slight incline in the distance. The tuner fixed that and is about 80% better than stock. I also noticed a slight increase in power. I didn't notice any improvement in mileage however I wasn't looking for or expecting an improvement there. I had read enough about the tuner to know that while I might get some improvement that alone was not worth the cost.
For me it was about shifting and power improvements.
I do use tow/haul when towing AND when I want more breaking help in mountains and traffic. Going up and down the Rockies it was used almost 100% of the time and worked great.