I did it last year. Hard for me to say whether it's worth it, seeing as how that's a matter of taste and I don't know how far a drive Hammond is for you (it's about 40 minutes to the park for me). Bicycle Illinois is basically a very small organization -I think it's just the one guy officially. You start in Forsythe park where he has a pretty decent assortment of food, and he and several helpers move two food crews to the various other stops. The ride is definitely interesting, as you bike a good portion of the bike path along Lake Michigan, and a decent amount through the city. The bulk of the ride is either on trails, or has a trail option. You can finish out a century by biking around Kenosha. It was quite hot the day I did it last year, but it was pretty fun overall, and I'll probably do it again this year (not sure whether I'll do the first one or the second one).
