The art in this is so good, and I love the format - simple and straightforwards, no sitting through mountains of text and cutscenes. Ero-development, status effects, and gameplay centered around H content.
There's always room for more in a game like this. Wish there were a bit more tentacle stuff, like they could've shown up as a mob throughout at least one of the levels. My disappointment at the hypnotist boss' lose scene not involving them was immeasurable, but hey. Could say the same of the robo-hands, like the 2nd boss would have his minions.
My biggest complaint is how picking perks from leveling up takes a lot of time and interrupts the flow. The undressing animations are also unskippable and sometimes quite long.
I really liked having multiple outfit choices, and the way Rena gets stripped. And I think one of the most fun parts is the option to get off the train, which can be blocked if she's restrained or post-orgam.
Hope the dev revisits the concept (and character especially - or just expands this game further) later on, but it seems they're working on something different for now.