I registered but wasn't able to do the ride, and based on what I've heard I'm glad I didn't. I did the ride three times five years ago and back. I recall one bottleneck in Central Park, but I remember it otherwise being a pretty smooth ride. The solution is simple: they just need to reduce the number of cyclists on the ride. There has been an explosion of cyclists in general in NY. I've been biking in Brooklyn for 16 years and while there are more bike paths, the sheer number of bikers has actually made riding in Brooklyn less pleasant. Plus, a lot of the new (30 and under) bikers, I hate to say, lack courtesy and don't seem to know how to share the paths with others. Not sure how to change their behavior, but better bike manners would really help.
Separately, for those who want to bike out to the Rockaways, note that the ride over the Marine Park Bridge is pretty harrowing if you have a fear of heights/bridges! The path alongside the bridge is very narrow (two bikes just fit with no extra space), and the floor is actually "see-through." The railing is also very open-feeling. I don't want to dissuade anyone from doing this otherwise cool ride, but I found the ride over that bridge pretty unnerving.