Let's be real: Annaleigh Ashford is the best thing about the revival of Sylvia, A.R. Gurney's play about an empty nest couple, Greg (Matthew Broderick) and Kate (Julie White), whose marriage is tested when Greg brings home a stray dog, the titular Sylvia, played to perfection by Ashford. (Robert Sella also appears in a few different roles throughout the play.)
Ashford is a comedic genius (she rightfully won a Tony for her performance in You Can't Take It With You), and is fearless on stage. She seemingly leaves all traces of vanity behind, rolling around on the floor, chasing other actors on the stage and just generally giving her body over to the hilarity that is a person playing a sentient, speaking dog. She is simply aces, and always a delight to watch on stage. (She's great on screen, too. Catch her on Masters of Sex.)
Aside from Ashford's performance, what I found particularly interesting about the play (directed by Daniel Sullivan) was how having a person playing a dog made the way we treat dogs seem curious. It really was like Greg was cheating on Kate with the dog, with him doting on Sylvia and making a fuss over her in ways in never did over Kate, and it was fascinating to see the effect that had on their marriage. (Especially because, at rise, Kate has no interest in having a dog; she just got her kids out of the house, and is looking forward to the freedom of not having a caretaker's responsibility.)
Your reaction to Sylvia, and with whom you side, will probably depend upon whether you're a dog lover, dog-tolerant or simply not fond of canines. I like dogs, but I like humans more. (Some of them.) For me, Sylvia is just a fine play, one to dig up when you have a star like Ashford to keep audiences wagging their tails.