I was a big fan of his several years ago. (When I was about 16 or so) The Soul Cages is the album I first really, really got into. Then I sort of went backwards from there. (The Dream of the Blue Turtles, all of the Police stuff, etc.) At the time I knew his solo stuff was jazzier than his stuff with the Police, but I liked them both just about equally.
I thought Ten Summorn's Tales was a great album as well. I really liked the video for "If I Ever Lose My Faith In You."
He lost me around Mercury Falling. Ironically, that's the first (and so far only) time I've ever seen him in concert. I wasn't overly impressed at the time, but maybe he just had an off night. (Plus I didn't really care for that album at all. I still think "Let Your Soul Be Your Pilot" is one of the worst songs he's ever written)
Then the Brand New Day album came out and I thought he was getting better, but for some reason I didn't get back into his music as much as I had before.
Like most everybody, I completely ignored Sacred Love.
Then earlier this year I saw Chris Botti with David Sanborn. I didn't even go for Botti - I went to see Sanborn. I knew Botti had played with Sting but I wasn't that familiar with him other than that. Botti just blew me away in concert. His trumpet playing is exceptional. After that I got the All This Time DVD just to watch Botti's performance. Then I really began to appreciate Sting as a bandleader for the first time - like a jazz bandleader. He's always played with some great talent - from Branford Marsalis to Darryl Jones (now with the Rolling Stones) to Botti.
The stuff on ...Nothing Like the Sun is incredible. Great playing.
So in sum, I think when his songwriting is good, he is good. He always has great musicians with him, but the songs aren't always there. When they are there, he's great. I know a lot of people don't like his music these days because they miss the sound of the harder-rocking Police. These days I prefer his solo career to the Police. I've always thought "Roxanne" was an extremely overrated song anyway.
I've been on a psudo jazz kick lately anyway - Steely Dan, Sting, Sanborn, Herbie Hancock (closer to "real" jazz), Boz Scaggs, Elvis Costello, Van Morrison, etc.
I love Miles Davis, John Coltrane, Sonny Rollins, and many other "real" jazz musicians, but for some reason I find myself listening to the above artists much more.
I hate having to put "real" jazz in quotes, too. But I fear the jazz snobs out there.
I used to work at Barnes and Noble in the music department, and I came across them every day. 
