The pound for pound ranking is premature and the expectations are the result of the skills he displays in the ring (speed, power, good body puncher, quick reflexes, defense, combinations, etc.) But with that said, he has a very good work ethic and takes every fight serious.
Skill-wise, he's not the next Floyd Mayweather. He's a combination of James Toney and Roy Jones Jr. (not in terms of greatness but you get what I mean so don't twist my words). He's offensive minded and athletically gifted while at the same time a very well schooled fundamentally sound fighter.
But he still has a long way to go. Appointing him boxing's next superstar is what's needed for HBO to generate ratings for their boxing programs which I don't have a problem with.
There are good fights at 135 that have to happen and that's the winners of Burns/Vasquez and Abril/Bogere. With Burns and Abril, you have two technically sound boxers that won't be standing in the pocket with him. In those fights, we will see some additional wrinkles in Broner's arsenal that we haven't seen yet and we will really see his real ring IQ and ability to make in-fight adjustments.
There should be no rush to 140, especially at 23 years old.