I just got back from tonight's show. There was a momentum-killing extended technical problem toward the end. Bartlett Sher eventually came out and explained that a robot had malfunctioned, so Higgins' study would have to be pushed out manually. After that, everything was fine.
I thought the show was mostly excellent -- one of the rare evenings where I spend full price for a pair of tickets and feel that I've gotten my money's worth (and my wife really liked it, too). The only significant weakness, in my view, is something that a couple of previous posters have noted -- some big laughs are being missed due (I would say) more to timing and delivery problems than to any intentional directorial effort to present something more serious. In fact, given some of the earlier posts here, I was expecting a purposely grey and dour production, but that didn't seem the case at all. Rather, it's a mostly lively evening with the occasional, brief flat spot.
Also, I liked the ending. As mentioned by others, Eliza seems to have come back to bid farewell to Higgins on a more tender note. And Higgins, despite his obvious sadness, is also (I think) somewhat exhilarated as he more fully recognizes the ways in which he and Eliza have changed each other.