Hey, guys. Thought that I would chime in as a Saints Fan who also has a soft spot for the Phins.
The book on Bush, from the perspective of a Saints fan, is not that different than the public perception of him.
I think that he has more value than people realize. Once he was declared a bust, people wrote him off. He was never a true bust. He just wasn't top-five worthy. If he had been drafted one round later and had the exact same career, people would be much higher on him.
Biggest problem for him has been health. It is a well-worn analogy, but he's like a sweet cherry-red Porsche that runs like it is on rails, but is in the shop 300 days a year. He's always getting dinged up, and his game does not really let him play through those dings. He needs to be close to 100% health-wise to really make an impact.
But, when healthy, he can make that impact. He's a mismatch nightmare for defenses. He's got great hands and can line up in the slot as easily as in the backfield. And his pass-blocking is very good (and very underrated). When he is in the huddle, the defense really has no idea where he will line up or what he will do--which really opens up other aspects of the offense if you have a QB who can take advantage of that. (You guys really need to upgrade Henne, to state the obvious).
To take that a step farther, if your QB really knows what he is doing, then Bush can be a great diagnostic tool. Putting him in motion before the snap forces the defense to tip its hand a bit. He demands enough attention that you can see how the defense reacts to him in motion and use that to figure out the defense pre-snap. Drew Brees did that all the time. (I mean, seriously, Chad Henne?)
Bush also still has the gamebreaking speed and moves that force defenses to cover him with something more than a linebacker or a plodding safety. This, again, opens things up for other players. And he's really good at making teams pay for under-covering him. It never makes it on Sportscenter, but his greatest contributions, I think, are not the 50 yard touchdown runs. It's when he takes a little flare pass out the backfield and uses his speed to outrun the linebacker and turn it into a 10 yard gain. He turns a lot of 4 yard plays into 10 yard gains by simply outrunning the defense to the sidelines. Keeps the chains moving and all that.
Finally, he will have occasional plays where he puts his head down and runs between the tackles, but those are rare. You can't teach an old dog too many new tricks, and Bush will almost always break plays to the outside that should go inside. Bad habits picked up from HS and college, I guess. You will see a lot of potential 3 yard runs turn into 1 yard losses because he tried to bounce it outside when the hole didn't open up for him.
Oh, and Bush has always had someone there--Deuce, Pierre Thomas--as the other back. The Dolphins will still need another running back to complement him. His health and running style will not let the team depend on him as an RB1 getting 300+ carries.
All that said, for a team that limits his touches and knows how to use him, he is a real weapon that will make the whole offense better.