It's going to be interesting to see how it stacks up to hon, especially since they have both had significant input from Icefrog. I wonder if just the simple fact that it's called dota will mean it does better than hon.
What concerns me is how they choose to monetise it, charging for it makes it a better game, because people can't create new accounts without paying, so they are less likely to be leavers. But if they make it free and then monetise through micro transactions, it will get tons of users and probably over shadow hon, but will be full of leavers because accounts are free.