I stayed at the Carriage House along with my family and 8 relatives and found the experience to be very positive. The rates are reasonable, the location right downtown just can't be beat, and the innkeeper Haziel is very accommodating and knowledgeable. The rooms were very clean and comfortable. The house is old and charming but well-furnished. The breakfasts were fantastic--fresh baked muffins, cake, fruit, and in the afternoon, homemade cookies. Haziel is very knowledgeable about the island and knows people in all the businesses to recommend, he knows what he's talking about, just listen to him.
We traveled with 6 kids and he was very nice about it, but our kids were well-behaved. I would say, don't listen to the negative comments about him, it sounds like they were posted by people who don't appreciate the B&B experience and would be better off in a Four Season or a Motel 6.
I would not hesitate to stay at the Carriage House again and would recommend it to anyone. Haziel is a real ambassador for Nantucket and has traveled and lived internationally, he's not just a "local yokel."
BTW, for those of you who have to go online when traveling like me, the Bean coffee shop has great free wi-fi and is a 3-minute walk from the Carriage House.