Looks and works like a rebranded NookStudy app, down to crashing the first 4 times I tried opening it*; only with marginally fewer features.
Also doesn't read .pdb files any more, which I think is a mistake considering how many Mac users must have by now.
It seems rather unhelpful of B&N to
hide and completely redirect to the new version any attempts to download the old one, if it's going to
a) be incompatible with pre-10.6 Macs, of which there is likely a significant installed base, some of whom won't be able to upgrade due to PPC, and
b) still serve Mac website users .pdb files which they now won't have anything they can read it upon.
But I hope this means they're working on getting the highlighting and note-taking syncable with actual Nooks, because that would be pretty cool.
* But the 5th one stayed up!