Just joined this year to get back into group riding and I've been quite pleased. They insist that new members take a group riding clinic before their first real ride, and I grudgingly obliged. However, judging from the other riders at the "clinic" I can see why they have this rule.
Anyway, I've only done the Sunday morning rides (usually the 100+ km one) and there is a very impressive turnout at Billings Bridge plaza. Then the groups divide by distance and subdivide by pace, so you can really pick exactly what you're getting into. I sort of wish that the rides started and finished somewhere a little nicer than a mall parking lot, but other than that, I've had pretty good experience with the club.
However, I'm really more into the mountain biking and since the Rideau Lakes tour my OBC participation has been practically nil... so I'm not sure I will renew my membership next year. Partly it might be the age gap, (I am usually the youngest rider) which can make me feel a little awkward at times.