Yeah, this is, by Shimo's standards, a small projects meant to test new mechanics, code, so on and so forth. It was never meant to be on par with either of his previous games, and the fact that it's as big as it currently is, when it's basically an experiment, is a testament to Shimo's tendency to go completely overboard.
So yeah, if this game is lacking compared to Ambrosia and Celesphonia? That's to be expected. It was never meant to be on par with them. That'll be the Serenoxia game, the one in the same setting as Celesphonia.