I started reading OOTS for its humorous take on fantasy roleplaying and fiction, and that remains its most evident characteristic. However, over time, it has developed strong characters and occasionally very thoughtful momoments, all without crushing its essentially playful nature beneath the burden of literature. It is also interesting that the artwork consists of stick figures; as with XKCD, the OOTS uses simplified graphical representation for amazing effect, stripping away unneeded detail to expose the core of story.
The OOTS website also supports a lively forum discussing all aspects of the comic. This is a great example of a virtual community, including people from several continents, able and happy to get together on a topic that interests them.