Gun Gale Online was a story that took place in the SAO universe, with a fresh new cast along with familiar faces. This manga is not a complete adaptation (the last chapter says to continue the story in the light novels), but it does feature one "arc" of some sort. The arc is mildly enjoyable. Even though there is cliche plot armor applied at certain places, the tension does seem to build in places with an abrupt twist or two. The current plot does feature some character development by the end of the book, though the overarching plotline leaves unanswered questions that would probably beexplored more in the light novel.

Overall, it's pretty short so it doesn't really waste your time and serves as a sample for the light novel.