It's in Open Beta, Three acts, three difficulties each act. (You play all the way thru 3 acts, on three successively harder difficulties). There are notes that they intend to continue developing more acts past that as long as funding supports.
It's a microtransaction supported game, but almost every single purchase is a cosmetic one (non-com pets, special spell effects, etc). The only one that is NOT, is extra storage space in your in-town inventory (shared between all toons).
The extra space is a bit expensive ($20 for 6 extra slots), however, considering the game is, in my mind, totally the D3 that D3
should have been, I'm ok with spending $20 to support them. Check it out, free to try, free to play, and NOT Pay-to-Win