I like it! I'm not well-versed in either of the universes, although I know generally about both, but it wasn't necessary, the story gave me enough information without me having to be familiar with the details (for instance I didn't see the end of Sunnydale).

(If there's a ghostly presence in NCIS then I missed it, and that's a show I /do/ claim to know! Admittedly it's been some time since I watched S3...)