I know it probably doesn't mean much to you guys, but take a look at some of the other Cave threads to appear on the board - they're in serious financial trouble right now and can't really afford to give away content for free, especially content that they previously charged $15 as an add-on for on the 360. Even if I were completely uninterested in playing it I'd probably buy anything they released just to support them.
I know people love to hate stuff like IAP and multiple versions but I'll gladly pay full price for anything they put out, and I think a lot of genre fans wil because they appreciate the availability. This stuff is hard to come buy in many places and even then it's somewhat expensive. <$10 is more than reasonable to me. I think the kind of people who buy these games will easily get their money's worth.
Black Label is a very different game IMO (and probably more accessible) and there's a Boss Rush mode (new for iOS) which has bosses from the original Mushi, which is really cool.
edit: I just want to know when it's coming. I'm going nuts waiting for it.