It's a beta version, it is the full game, you can play until the end and finish it. After the sewers the game opens up a bit, more unique encounters, sidequests and minigames. I would say after the sewers you have gotten perhaps 25% through it all, but that depends on how thorough you want to be. A full playthrough usually lands somewhere around 8-12 hours.
Originally there was supposed to be a joke where you never got to see the face of the Veteran, where his picture did not show his face. One trophy you get shows the whole sewer family, his face excluded, but I went with showing it in the end. I will consider making him turn around.
Glad you liked it, there are a lot of skills coming up as you progress which you can freely swap between outside of combat in the menu, some trophies also change a lot such as the stethoscope which auto-uses items that takes away debuffs or status conditions without taking time out of the turn order. It's going to get cooler, it might be worth continuing. Combat is a lot more like old FF than pokemon at its core, there is a lot of turnorder manipulation possible.