A few random thoughts...
First up, if the reaction here means anything, this is one of the biggest format launches in Phoenix. I started adding up the "views" of the threads related to Free FM's demise/Jamz' debut, and stopped counting after ten thousand. Add to that the 8 pages of comments (both good and bad) on azcentral.com, and it's clear that this is the most talked-about format flip in a very long time. You might call it "weak," but you took the time to log on here and call it weak, right? That means you were listening, and so were a lot of other people.
Next up, I was flipping between Jamz/Kiss/Power sitting on the I-10 on my way home today, and my first impression is that Jamz wins the signal processing battle hands down. I don't know if they tweaked it just for this station, or if its just because that signal is a blowtorch, but it sounded really, really good. Power is flat and a bit distorted (with some occasional static), and Kiss is tinny compared to Jamz.
The imaging is tight...simple and straightforward...which is exactly what you need when you're launching a new product.
The next big questions for CBS (and for Bruce St. James) are: Who's the airstaff? How will they promote it? And how will they sell it?