Yes, my father in law HAS one, and my brother in law HAD one. I haven't put a bunch of miles on them, but at least 200 miles, on country roads, highway, city, mud pit, etc.
I didn't notice much turbo lag at all, and neither one of them has had transmission issues. My father in law has about 30k on his. He is able to get 22mpg going 75.
Where the ecoboost shines is providing similar gas mileage to the competition but more tq all across the rev band. It makes driving a heavy truck, and towing feel like less of a burden.
The one thing I really hate about the trucks, though, is the seats. They are awful. The cushions have broken down and you can feel the frame already, and my father in law weighs about 250lbs, so hes not a tub o lard.
Just my observations, your mileage may vary (obviously has).