This is really a play review, but I read it as a book so I'll review it like a book.
Like most Stoppard plays, Arcadia jams a lot in and seems to be a bit like Pontius Pilate, "always asking what the truth was and never waiting for an answer." (Bill Mallonee's lyrics) After the end, you can provide your own answers, so I have no problem with that, but it's that aspect that keeps this from the top of the list.
The play is set in a single room in an English estate, with half the scenes in the early 19th century and half in the late 20th. There's fractals and Lord Byron and garden history and academic jousting among professor types and affairs and a duel and thermodynamics. I admire how Stoppard mixes it all together, and the point of this play is more the synergy between the disparate components than, say, the hilarious wit of Rosencrantz and Guildenstern are Dead (still my all-time favorite Stoppard).
A few passages say some interesting things about science but I'm still left feeling that the play is not really about science or how things come together, but it's more about how things fall apart. I could wish Stoppard had taken it in another direction but there's enough pieces on the table that the "other direction" is still open to the reader and this could provoke a fascinating conversation if seen as a play rather than read as a book. That's probably the point, but without someone to put it on around here, I'm left with the book.
It is thrilling how the elements whirl around each other by the end of the play, and probably worth a second reading to see more of the structure behind that motion. There's got to be some recurring motifs that serve as fractals in the play itself that I didn't detect the first time through. I would just prefer a play that was definitely worth a second reading to one that was probably worth one, and if you're going to be provocative about the nature of scientific discovery and the heat death of the universe, be provocative and bring that aspect out a little more. More science, less garden.