Love free things? That's a silly question, everyone loves free. That's why you'll like this story. Valve has launchedDota 2: Spoils of War free to play, with free access to all heroes, though admission into the game is still selective. Although Valve isn't calling it a beta, there's still a little work that needs to be done before they let everyone onto the servers. One of the things I'm most happy about is that, while there are microtransactions in the game's store, what you buy won't affect gameplay, as they're customizations only. You don't have to buy stuff if you don't want to, though, because they've set it up similar to how Teamfortress 2 is set up where you can get random item drops.
Going along with the customization store, Dota 2 has a Steam Workshop where you can submit your own ideas for customizations, and if Valve likes them enough they'll be implemented into the game and you'll receive a percentage of the profits. This is cool because it not only allows the community to be directly involved in how the game's characters look,, but also because it gives Valve a method to make some money off of the game while still allowing people to play for free and still be competitive. If they allowed you to purchase upgraded weapons and such, the game would quickly become unfair as the people who buy upgrades would be able to win more easily than the people who could/do not buy upgrades.
Admissions to the game is still selective, because Valve's servers aren't ready for the overload of people wanting to play, but you can try to get in by following the links at the bottom of Valve's Dota 2 page. FAQs can be read here, and you can view the Steam Workshop for Dota 2 here.