This answer applied to the first edition.
I used this as input to my seder. I printed copies for my guests (and sent people home with them), had chosen a couple questions to bring up in discussion, and had anticipated reading some answers from the supplement. No plan survives contact with reality. :-)
We had a really talkative bunch, which is great! (Almost three hours to get to the meal, and there were only eight of us.) And other people brought sources and ideas too. So what ended up happening is that questions got asked and discussed without much verbatim reading from any of the sources that people had brought. Several questions that others asked were answered in Hagada Mi Yodeya? and I ended up summarizing those answers (being, you might say, already very familiar with its contents).
The questions from our haggadah that ended up getting asked were:
- "If God had not delivered us...we would still be slaves?" (I brought this one up)
- Why is the wicked son sanctioned for doing what the wise one did? (I asked this one too)
- Did hardening Paro's heart mean he wasn't responsible?
- How would Har Sinai without torah have been enough?
- What do you do with kos shel Eliyahu (asked by a guest on the way out the door, not at the seder)
- Why do we sing "Echad Mi Yodeya"?
This year's s'darim (I was a guest at the other) were the best seder experiences I have ever had, individually and certainly collectively. Hagada Mi Yodeya? had a lot to do with that for one of them. (While the leader of the other had a copy, I don't think he had time to do much with it. Maybe next year.)