Oh, I had this guy too:
He is a fucking BOMB in limited, especially if you're B/W. Whereas a lot of the removal we saw in Innistrad (Smite The Monstrous, Rebuke, Victim of Night, Avacynian Priest) was conditional, the Flayer can destroy any non-hexproof creature. He combos well with guys like Village Cannibals, Thraben Sentry, and Unruly Mob, and he has plenty of desirable pitch targets: Elder Cathar, Doomed Traveled, Loyal Cathar, Masoleum Guard.
Also, here's a fun ruling from Gatherer: "Another double-faced card that becomes a copy of Loyal Cathar and then dies will return to the battlefield with its back face up."
Fun with Mirrorweave?