A lot depends on where your friend ends up living and working. Safety is a concern; as noted many areas can be dangerous. The population re-shuffling that occurred after Katrina has changed the landscape in terms of safe/unsafe zones; the projects are largely depopulated and don't generate crime in their vicinity like they used to; however, many areas that were once considered safe are no longer so. Night-time riding is especially problematic; service-industry employees biking home late with their nightly pay are targets.

That being said, the flat terrain is very bike-friendly (not so much the roads) and there's a large community of bikers, especially in the Marigny/Bywater neighborhoods. There's also an active group of roadies that ride almost daily on the Lakeshore and levee trails. Biking here is a wonderful experience and I do it whenever I can; my car will sometimes spend the entire week in the driveway.