Well, today most of his jobs are still in jazz-styles, from trio to big band. The diversity depends on the other musicians he played with. He started in the 80ies with jazz, later on he played also in funk and fusion bands. I think he there first played with American artists, and then more with Scandivian. You can hear it in his solo albums, "Music" and "Urban Life" from the end of the 90ies are fusion and funk with american influences, Zooming from 2005 is something complete different where you would say it has Scandinavian influences. That's simply because over the time he played with musicians from different parts of the world. Not exclusive, but mainly.
With his newer solo albums (Zooming, Shapes) I don't know how to call the style. It's not the classic jazz, the main focus is every time on the song itself respectively the idea. It's not spaced out with soloing, it's just music.
He says with Zooming and Shapes he has found his own sound, so if you want to know for what he want to stand for nowadays, listen to Shapes (and Acoustic Shapes, Shapes Live in Concert) or wait till next month when "Round Silence" comes out.
I would say the old solo records were not an exceptional level of music, they were just funk and fusion, sometimes good and often standard. But that's my personal opinion, with fusion you can't touch my heart of music.
One of his main influence in his playing is Steve Jordan (get the video "The Groove is here"), and he personally likes e.g. Mel Lewis.
Just look at his biography on his website. With the list of the artist he played with, you can imagine how his style changed over the years, where he got the different inputs.
http://www.wolfganghaffner.com/
