Ultimately, I evaluate any anime series, including chibi short spinoffs like this one, based on how well it meets the objective that it sets for itself. The main Sword Art series attempts to tell a sweeping story about how players hold on to their humanity in a virtual world, and while we can debate the efficacy of its attempt to meet that objective, Sword Art Offline sets no such lofty standard for itself and thus shouldn't be held to the same kind of standard.
This series is, in every sense, bonus material: it's meant simply to offer a few laughs and smiles to fans of the series who have already watched all there is to see, but want to see more of their favorite characters. So, painting with broad brush strokes, this miniseries gives us just that: a series of comedy sketches featuring most of the prominent SAO cast members, the humor of which is primarily slapstick, but for what it is, that sort of approach *works*. Is it high-quality entertainment? Perhaps not, but it's certainly good for a few laughs, and some of the visual gags are indeed pretty funny. The show maintains a decent sense of comedic timing, and for what it may lack in subtlety, it delivers in exuberance.
If you enjoy hearing seiyuu clowning around a bit, you'll probably enjoy this series. It's the kind of show you probably have to be in the right mood to enjoy, and for better or for worse, I found myself laughing my head off at it, even though I knew that the humor wasn't particularly well-developed. The humor may get a bit stale if you watch everything in one sitting, so perhaps try breaking it up and watching an episode or two during a lunch break when you need a quick anime pick-me-up. Overall, if you come in without too many expectations, I think you'll find this eager-to-please miniseries entertaining. If you find it's not your thing, well, that's what the "dropped" category is for on our lists.
Oh, and the episode in which Heathcliff is a guest contains some foreshadowing for the Ordinal Scale movie. That combined with the trivia sections is probably the only plot-relevant reason to watch this series. Most of it is just for fun.
