Yeah, it sounds like a total racket. Unless they can deliver an impressive amount of new content monthly, I say fuck them.
I am pretty sure the game will probably bomb. Unless they buy off reviewers, it's going to get 7s and 8s, and this season isn't a good time to release good, not great games, and expect the folks to make them hits. Especially when a large portion of their model is probably based on that monthly fee catching on.
I could be wrong--good Diablo-esques don't come out often, so maybe the people are hungry--but I really don't see this being very successful. Flagship has promised the world over the past several years, and they have delivered, I dunno, Portugal: Nice place, but would you really want to buy it when presented with Spain or Brazil?