I'm surprised by reactions to this. I think this is a great move for Detroit. It gives them exactly what they were lacking - a scorer and shooter who can spread the floor. Their defense will be rock solid with the Smith move, and they've added serious firepower.
You can judge his efficiency but, at the end of the day, he's a prolific scorer and extremely difficult guard. His percentages suck because he has a tendency to take horribly difficult shots. But all in all, he's a very good shooter.
If healthy, I can't think of a better back-up for Jennings in Billups - still very talented, can also fill it up, and could be a great influence on him as on of the steadiest PGs in the league. Can play some 2 also, if needed.
I immediately thought "Who is the 2?" Caldwell-Pope is very, very good and can improve on both ends (I watched him here at UGA this season). Given their youth, this won't be a great team. But they'll improve and I absolutely expect them to make the playoffs.