The version 1.0.0 designation implies the developer (a pseudonymous creator known only as "PixelSage") actually went back and polished the original 0.9 beta. They fixed the pacing, added a CG gallery, and—most famously—removed a controversial "Friendship Exit" that beta testers found too cruel.
The jump from 0.4 to 1.0 is massive, effectively doubling the game’s content and providing the conclusion that long-time fans have been waiting for. Sassy Girl -v1.0.0- -Completed-