Daniel,

I can't speak for Mr. Riley but I'd say that it's worth your time. It helps that it's pretty short (4-5 hours for an initial playthrough), and it does tie into the SH1 mythos, but it's nothing terribly essential and kinda just muddles SH1 a bit more. It's certainly more playable than SH4, although I think SH4 is a more thrilling experience, if not a better game.

That said, I prefer the enigma of Silent Hill as opposed to the cult behind the town, so your mileage may vary.