I have to agree with a lot of that. SoL:C is not a bad game (I do enjoy playing it), but it does have a number of weak spots. The cardboard characters are one, but overall, what more do you need in a simple hentai game? You are simply meant to be the white knight, and everything else flows from that. I can live with it. The part that bugs me though is that no attempt is ever made to integrate the harem aspect into the storyline. He just loves them all and they all love him, and it's jarring to see him express his undying devotion to one girl, only to do the same with another in the next scene (the only worse one I've seen in that respect is Lewd Town Adventures). I'm not a big fan of the overdone isekai/chosen one aspect either, but whatever.
As for gameplay, it suffers most severely from sametimeitis, the worst I've seen in any of the dozen I've played so far (A House in the Rift comes in second, though it is a superior game in almost every other aspect). Almost all of the important interactions happen only at noon, and often only on specific days. And automatic events tend to hit simultaneously, preempting your planned activities and forcing you to grind for a-whole-nother week until you can try again. It can get incredibly frustrating. Long waits, several days to a week or more, between scenes also slows things down a lot. One thing that would really speed things up would be to randomly meet characters at different times of the day, in different places (for general interactions, at least). Turn the city park (downtown), library, lake, and mall into more active locations, and expand student interactions into the mornings and evenings, and the whole thing would feel more dynamic.
On the plus side, at least the game is fairly simple and pleasant to work through, and it does not suffer from the "I'm so in love with my worldbuilding that I'm including hundred page wall-of-text cutscenes every ten minutes to tell you all about it" that some of them do (I'm looking at you Harem Hotel and Lucky Paradox-I just forward through that crap as fast as my spacebar can go now). It never gets bogged down in heavy-handed complexity.
I will say I also like some of the little touches. The interface is reasonably intuitive, and finding the secret stash cards is fun, as are most of the little bonus side scenes. And while I may possibly be in the minority, I am thankful so far that it is not too overloaded with fetish stuff either. I can put up with the occasional footsie scene or whatnot, but some of these games go way overboard. I just hope and beg that if preggo is introduced that it can be completely disabled. I want to play hentai games to escape the real-world consequences of sex, not wallow in them.