Each of the movies looks very good in HD, with, as you would expect, the A/V quality getting better with each movie. There are extras for each of the movies, including commentary tracks on all three movies, deleted scenes for every movie, featurettes on the effects, making of documentaries for each movie, an extended edition of Riddick, and more. So, if you like watching bonus material, there is a lot there for you.
Overall, the movies are a good blend of action and, with the first and third, horror/suspense. The acting is okay to good. Diesel is what he is, but each movie has a good supporting cast that makes up for his shortcomings. Between the three movies, they include Cole Hauser, Keith David, Alexa Davalos, Karl Urban, Tandie Newton, Judi Dench, Colm Feore, Katee Sackhoff, Keri Hilson, and Dave Bautista. As long as you do not go into them expecting academy-award-winning material, they are enjoyable. The dialogue can get clunky and/or downright dumb sometimes, but the action sequences generally make up for those moments. So, if you like action movies these are good ones to check out.