First, those of you who watched this as a three-hour movie with 30 commercial breaks must have seen a royally butchered cut as the R2 DVD is four hour-long episodes.
Second, those who claim that the BBC are not as good as they used to be are, perhaps, not quite fair, but not totally wrong either. I imagine they are comparing Charles II to Elizabeth R; I, Claudius; or The Six Wives of Henry VIII, and yes, it's not as good as they were. But then, neither were the other series the BBC were making at that time.
But if such comparisons are not entirely fair, they are also inevitable. Elizabeth, Six Wives and Claudius were televised plays. They worked due to the interaction of great scripts and great acting. The costumes were icing on the cake; the direction and camera work were capable but never drew attention to themselves. These teleplays continued a dramatic tradition traceable back to Shakespeare. They were *plays*.
Charles II, on the other hand, as well as other historical dramas done by the BBC these days, has abandoned its dramatic lineage for cinematic aspirations, especially as technology becomes more affordable. I don't consider this a bad thing, though I do think it failed, just as many teleplays of the golden era failed in their attempts. There's nothing wrong with bringing direction, camerawork, production design, etc. to the fore. Unfortunately, the scripts suffer, at least in this case. The viewer is innundated with flashy techniques like handheld cameras which achieve nothing other than making the show look modern, or a seven-minute long single take near the end of the final episode which contained about three minutes of dialogue that actually advanced the plot or developed the character in meaningful ways.
Is it worth watching? Yes. But don't compare it the greatest costume dramas ever made. Take it for what is, and it's a fine drama.
