Worth the buy just to see how Early Access can be done right, full stop. But it helps that the game is fantastic, I guess.
Great music, graphics that look like a great PS2 game with perfect IQ, frenetic but highly fluid action that runs well even on a fairly poor PC. One of the best twin stick shooters I've played; controller recommended but mouse works fine. Note the game is pretty hard, and score MATTERS; your "life" is a battery that constantly drains (not by taking damage, by time), and you get battery pickups by scoring. You will have to be good to beat this game.
As for the Early Access, this is how it's done. From the very start it was clear what was done, what was being worked on. The place holder graphics were clearly not final but polished in their own way that it's not quite so jarring to play an unfinished level. More than enough good music to make it feel like a final release, and gameplay is extremely tight.
Overall it feels like you're playing a curated selection of a finished game rather than unfinished chunks of randomness that the creators will polish later. Everything you experience feels polished enough to let real people play, even if it's not finalized it's still playable and not too hard on the eyes, ears or fingers.