Cymbeline is probably the most peculiar of Shakespeare’s romances, and they are, on the whole, a fairly peculiar lot. It has a fantastically improbable sequence of events — more improbable even than The Comedy of Errors or Pericles. Lost children are found after twenty years; those thought dead turn out to be alive; people get smuggled places in boxes; complex disasters all turn out to have been subtly changed by connivance or mere happenstance, and everything turns out well for the good guys and badly for the bad guys (which, as Oscar Wilde said, is what “fiction” means.)
Shakespeare is noted for the depth and complexity of his greatest characters. Here, on the other hand, almost everyone is a type. At the same time, it is also of a piece with the more political dramas (Richard II, Macbeth, and most of the Henry plays). To some measure it is designed to tie the current monarch (James I) in to both the British and Roman forebears in England.
It is also by turns introspective and wonderfully lyrical. There are pieces of the play that rise to some beautiful language, even as the plot is taking a yet more implausible twist. Take it as it comes; don’t be too fretful about keeping in touch with plausibility. Many have found that it is, despite all expectations, one of their favorites in the Shakespeare corpus.