I was so proud of myself for coming up with cHI almost immediately for 14A: Greek letter that's also an M.L.B. city on scoreboards), but in the end it was what cost me a perfect puzzle. I didn't check the down, and AcP didn't make any sense for 1D: 99¢ purchase, often (APP). Always check the crosses!
OK, now that that's out of the way... I liked this theme of PAIRSOFCARDS (56A: Some poker holdings ... or a hint to 20-, 24-, 30-, 41-, and 52-Across). Each theme answer (and it sure seems like the theme is dense in this one - six answers!) can be broken into two words, each of which can be put before "card" to make a common object. "Credit card," "report card," "hole card" (poker reference), etc. I tend to like this type of theme, and this one is done particularly well, I think. The revealer itself is probably the weakest link, as it sounds a bit odd.
You know, maybe I'm getting a little soft, but it almost makes me smile to see things like ELOI, IPOD, and TOPE in a puzzle. They're like old friends. ACEY and AAS is pushing it, but overall, there wasn't too much of that kind of thing.