Maybe to your surprise, but a lot. I'd wager 4 hours of content if you stop and read everything, bit I might be overestimating it. Also it's more complete if that makes sense. Where "old" Genex Love leaves off has much to be desired from both the story and its characters. Not to mention, the sequel is being made and you won't be able to transfer your data from the first game(cause the sequel is more of a continuation rather than a brand new game) and have all the stuff you had in the first game, including money, items, powers/levels, and lots of things will not make sense.
I've typed your eyes off here but all in all, the latest version is imo a better version of Genex Love. But I won't force you into anything. You can technically not play the first game, and get a jist of all that happened, but it is worth it's price tag if you ask me.