People play notoriously loose on play money sites. So, while you'll get a LOT of practice recognizing "possible hand combinations", you won't see a lot of "real poker".
I play every day on NLOP. It's also free, but you can win real cash and prizes. (Ads fund the prize pool.)
It's best to get "invited" there. You get a few extra tokens to play with. Not NEARLY as many perks as you got a couple weeks ago, but still not a bad way to go. Let me know if you have questions about it.
PS It's also pretty loose, but the more that's on the line, the better poker that's played. Much better than the total social poker I played on before.