When I heard Capaldi as Richelieu had to leave (for Doctor Who) from this show after the first season, I was concerned about how they'd continue the storyline of the series without a RICHELIEU! Yet the screenwriters managed to keep me interested with new ideas and villains. Others have mentioned it gets off to a slow start, but overall I have enjoyed the entire series as a whole - full of fun, action, romance, etc. Just what we expect from any version of The Musketeers, right?
I watched the series on TV, so I have yet to watch through the entire blu-ray set, but so far the quality looks good! Wouldn't mind more special features, though.