The page also notes that while Larian will be updating the game regularly, save games will "not be compatible between versions." Sooo maybe don't get super attached to any adventures you start until Divinity's final version is released. Of course, the final version will include an RPG maker, so you could just get familiar with Divinity's mechanics and then make your own adventure.
Larian is encouraging all participants to share their thoughts concerning balancing, bugs and potential improvements on Divinity's discussion board. If you're interested in helping or just itching to venture through the first chunk of the game, $39.99 will get you an Early Access copy. You can also go for the $59.99 double pack and try out the Early Access multiplayer with a friend.