A early difficulty curve is a small price, to play to a fun game with incredibly depth. And its free.
Combined a game this good with a free to play model focused on game play (absolutely every thing can be bought is cosmetic and doesn't provide any game play advantages, maybe with the exception of items so cool that it distracts the opponents) make it that much better.
The Dota2 Client is the icing on the cake, allowing you to spectate live games, replays even watch tournaments and even videos of hero abilities to help the players learn.
And if you have a few friends you can drag along the experience can only get better
The initial challenge may seem too much but once you get your toes in the water you'll discover a world full of depth, challenge and more than a few holy s#@&! moments.