You can hear a song off his upcoming album here:
http://music.download.com/paulmccartney/36...l?tag=slide_hed
I really like it. I may not be a fair source though because I own all of his solo albums/wings albums/ and obviously all of the beatles stuff, and I love it all.
Give it a listen.
I will say that if you didn't like him in the past this wont change your mind but if you are a fan the you will love this song. The reason I say that is because while it is a good song its not ground breaking and it is definitely his style of music.
McCartney is a genius though. I'm convinced the man craps out hit lyrics.