[Matt R.]

I like it... I think his turn bet was small enough for you to call (and obviously the river bet is after you call the turn). Looks like a missed flush draw or a mid/low pair to me, and your 99 is ahead of most mid/low pairs (including JJ and TT... most people wouldn't even limp these), so I think you have the pot odds to call here. I think he doesn't have the ace often enough here for this to be profitable.

Edit -- pot odds isn't really even a necessary consideration, as I think you're usually ahead here. What I meant is that his bet size relative to the pot seems really weak, so I think your 99 is good often enough to call.