As for the demo, the first thing anybody who has played The Darkness will notice is the main menu screen looks very, very familiar. It's also worth watching the "Introduction to Jericho" because it gives all the exposition so that the actual demo is pure gameplay -- be warned though, the voiceover guy is incredibly annoying. Although there are seven members of the Jericho squad, you'll only play as three in the demo. Controls are intuitive for anyone that's played an FPS and switching between bodies works really well. The combat takes a little getting used to, but certainly a demo worth checking out.
Update: Updated PSN information.