I've been riding bikes in downtown JC for the past 12 years. It's got much better in the past few years with the PBL's starting to appear. North and South bike lanes are still shared with cars, so as long as you're comfortable with that it's fine. I recommend riding defensively, assume cars will not check their mirrors when turning, not yield to you in general, and entertain the possibility that cars will run stop signs. Hyper awareness and visibility is key.