[Nightwish]

This is tricky. His river check almost always means that he doesn't have an A, so the key question here is whether he'd cap with JJ and smaller pairs preflop. I doubt he'd cap with TT or less, so it all comes down to whether he has KK or JJ. It seems like a tossup, except that

(a) JJ is more likely to check the river than KK
(b) if he has QQ, your bet has a very slight chance of getting him to fold

So I say it's a value bet, but not by a whole lot.