Christy, our guide, was amazing. She was engaging and funny, and made our pub crawl so great. Whatever her salary is, raise it.
We went to 4 different bars, had about 3 stops in between them for some historical background and facts. Total of about 3 hours, plus the time we stayed at the last bar with some other participants.
In terms of the rest of the group, I guess it depends on who you happen to overlap with. We were 4 different groups of people, and mostly engaged in conversation with just one. It was still fun having an organized route of bars. Discounts are not huge but you don't go on this for that.
Highly recommend!