A thoroughly enjoyable bit of interactive entertainment for medium- to long-time fans of Homestar Runner.
Something that's important to understand about "Homestar Ruiner" is that it was clearly done with already existing fans of Homestar Runner as the target audience; people who have never heard of Homestar Runner still might enjoy it, but it's probably not the best way to introduce someone to the Homestar Runner "universe" simply because knowledge of that universe is something of a prerequisite for full enjoyment of the game. Fans, on the other hand, will no doubt enjoy playing through something akin to a "day in the life" of Strong Bad, even though no battle axe lessons are attended.
Overall, existing fans of Homestar Runner should purchase this episode or the season pass: you're pretty much guaranteed to either really enjoy it or at least somewhat enjoy it, and it's an easy way to support the creative work the Brothers Chaps have been putting out almost every week for the past eight years for free.
For those who aren't familiar with Homestar Runner, I would recommend visiting homestarrunner.com and watching a bunch of toons, emails, and shorts. If you like what you see, give Homestar Ruiner a shot.