It's back in the Appstore and still free. So far I'm loving how polished this game is. I'm only on the 2nd campaign level so far, but I'm enjoying the diversity of what players I do have. There is a lot of additional characters to choose from (as the description states) that have some beautiful artwork and diversity as well. There is an online mode for PvP too, though I can't confirm it's asynchronous. As far as iap goes, you can buy coins, gems, and additional content (that's yet to be released); I don't see any pay walls the way it's set up either.
I'd recommend any TBS fan to get this while it's free. The small file-size alone was worth the download.