You can definitely buy the game by itself from PSN.
Regarding the quality of the game it's okay. The in-game cutscenes are awful, though they mostly appear at the beginning of the game and the pre-rendered ones are fine. For the actual gameplay I'd recommend constantly backing up your save or changing which slot to save to as the game has crashed for a few people when the game was saving which corrupted the save file. There's also one trophy which is glitched for some, so keep a backup before getting that one if you care about platinum. Other than that the port is fine. It's definitely not as bad as everyone says as the gameplay itself is fine.