Yes it is. The International is basically "Dotacon" so to speak. You get all that stuff, fun online events to participate in (like trading player cards to complete teams in your Compendium to upgrade your courier), predictions, fantasy Dota, a battle booster that lasted over two months (basically gets you more frequent and rarer cosmetic items).
So you didn't want to pay $10 for a Compendium? That's fine too. Either way you can watch all the matches of the tournament in-game for free as well as the same high quality, high production value streams as everyone else, Compendium-owning or not, watches.
On top of that, part of the proceeds went directly into the prize pool for the tournament.
Indeed.