This guy is one versatile connection.
1) He'll give 1 for 1, which is a pretty good deal.
3) He's also a pseudo Emergency Shutdown that can be used at weird times during the runner turn! After running on HQ, you can run on a remote safe in the knowledge that any unrezzed ICE will be very expensive for the corp (sad days if it's Vanilla though). I believe the window on him is such that you can either force the corp to rez twice or simply shut it down and bypass entirely. (Please correct me on this if I'm wrong!)
Since he's unique you can't pull off completely absurd multi-James combos during a run without Street Peddler, which is probably for the best. Easily one of the best sources of (one and only one) link in the game, and a great splash in almost any faction for his great ability.