I thought this one was a prequel based on the, erhm, "0". But oh well, I'll play the first one soon then.
To explain would be to spoil Steins;Gate. You'll thank us once you've finished it.
I'm generally a fan of playing games in release order anyway. Even if this were a prequel, I'd still recommend playing the original because it was released before it.
It's like saying people should play MGS3 before MGS1 or 2, which makes no sense because MGS3 is a continuation/evolution of the plotlines, themes and gameplay of the previous games, even if chronologically its story takes place before them.
If in doubt, always play in release order. I don't want to give any specific details about why that's the case with this game, however.
Anyone else can't decide immediately which version to get?
I want to play in bed, so probably the Vita. But then again, I could use Remote Play for that, and still keep access to the 1080p art and PS4 system features.
If it's cross-save, I'm getting both. It's probably not though, is it? I may just grab it for Vita for continuity's sake, since I have the original on Vita.