This is probably my favorite Pokémon game of all time, and it's mostly because it never made me feel like what I was doing was pointless. The writers actually seemed to care about the story in this game, compared to other where the story is just a reason to move the player to the next gym battle.

It's characters are also just very well written, in many fangames I find that a lot of the MC's allies are just uninteresting to actively annoying but rejuvenation manages to almost completely step around that. There are characters that I do find to be very annoying, but MOST of them do actually get character development or manage to grow on me. The characters aren't all perfect of course, one of the characters is acknowledged by the game to be completely irrelevant to the main story, maybe it's something to be changed in future versions but I'm not sure. Devs also seem to just have taken a character from Umineko too, Kanon in Umineko is a magical servant who believes that his nr 1 priority in life is to serve his master, and Kanon in rejuvenation is a magical servant who believes that his nr 1 priority is to serve his master.

The story does have some flaws too. Some of the villains are just irrationally evil, but only sometimes. An example is Neved, who tortures a teenager because her dad was rude to him, otherwise Neved is a pretty rational person and one of the more "good" people in the evil team. And for most of the current content you will have absolutely no idea what the goal of the evil team even is.

Overall though, the game is great. Maybe it's because I have played it so much, but if I were to tell a person to only play one pokemon game, this would be it.