Wasn't quite sure what to make of this when I first heard about it, as I have never seen Rocky Horror. I thought the overall thing tied in quite nicely to progressing Will and Emma's storyline, but not by much, and in this way, seemed to have forced this Halloween themed episode.
Whilst it was good that they didn't just recreate the musical, I felt that it was too truncated and did not in essence capture all of what Rocky Horror is supposedly about. Whilst they did perform all the songs on the episode from Rocky Horror, I didn't feel that much more connected to it.
Definitely not as good as the Britney Glee Episode... will look forward to Gwyneth Paltrow in two episode's time!