Well, it's up to you!
If you can't wait for more content, then go for it, but if you'd prefer to play the game blind, then better to wait for the full release. Beta access will keep updating (updates take long though, as I work alone) until full game, but it may also have unfinished/placeholder assets.
I'll only close the rewards once the game is near completion, and I'll be sure to announce it, so you can also wait it out.
(Beta access also includes your name in the credits and earlier access for the full release.)