The play is satirical, even by G&S standards. In it, the sleepy south seas island of Utopia has become infatuated by the culture of Great Britain, and decided to adopt it wholesale. We watch as they pick up British customs, replacing island traditions such as how they run their monarchy. ("Despotism tempered by dynamite".) The flavor is surprisingly modern, even timely -- the island incorporates as a Limited Liability Company to evade its debts, and the King's travails with the island's newspaper could easily be a parody of modern celebrity-obsessed media culture.
Of course, it wouldn't be Gilbert and Sullivan without an assortment of romances, in this case wrapped up in a plot that centers on the difference between the theory and practice of civilized manners. The King's daughters have been tutored in the ways of a proper Englishwoman, to the periodic frustration of their various suitors, in a plot that could easily be transplanted to I Sebastiani simply by changing the names of the locations. And Act II opens with the romantic lead delivering an aria about how the physical effects of love makes it difficult for a tenor to sing properly, one of the finest pieces of self-referential music I've ever heard.
One odd detail: the play quite distinctly takes place in the Gilbertverse. It has a number of little throwaway references to earlier Gilbert and Sullivan hits -- again, a sort of self-aware attitude towards media that I usually think of as more modern than it really is.
The performances range from good to excellent, as befits so long-standing a troupe. (The Savoyards have been running for nearly 50 years.) Good comic timing and a lot of fine stage business, along with solid singing. The music is *not* the most inspiring G&S -- I assume that the lack of anything really hummable is part of why the play is so obscure -- but both the orchestra and singers handle it well.
It's running Friday and Saturday, at Lincoln-Sudbury Regional High School Theater (really quite a good stage and a big auditorium). So if you find yourself with some free time in the next couple of days, I commend it -- it's a chance to see a good performance of a pretty rare play that feels almost as timely today as it did when written...
(ETA: Oh, and for the contra dancers in the crowd, one of the patter parts is played by well-known caller Tony Parkes...)