The International tournament was a blast and everyone in the esports industry praised and thanked Valve for such a wonderful event. To hear about the success and ratings of the International from Valve themselves Gamespot interviewed Erik Johnson from Valve.

Erik Johnsons in his interview says that Valve's goal at the International was to gather the most talented teams all over the world for a weekend event and make the event accessible to the Dota community. He mentions that Valve's aim was to create a direct relationship between the Dota community and the creators of the product.

Concerning the development of Dota 2, Johnson stresses that their "job is to figure out how to allow those people (star players, personalities and teams, Ed.) to have a direct relationship with users." The pennants introduced for The International were "a good first step", according to him.

Various teams had overheard that Valve expects to return to Seattle next year for The International, with a plan of staying there for an additional 3 years. Is this true?

We haven't thought that far ahead yet.

Blizzard this year launched their World Championship Series, while Riot is currently in Season 2, each with dozens of events around the world, with live finals. Currently, The International is still a one-weekend event, has there been any thought to doing an entire season championship, and/or to have more LAN events for Regional/Qualifier finals? Do you think this is necessary?

[...]

The big factors in how invitations for The International will be decided are both how active and how successful a team is throughout the entire year. Our goal is for teams and leagues to be able to put together high quality tournaments throughout the year, with the best teams in the world competing, and our guess is that, if we ran a year round season, we wouldn't run those events as well as existing tournament organisers.
You can read the entire Interview on GameSpot.

Sources: GameSpot