It's one of those games... While good, it's hard to compare it to other VNs, while I completely understand this wasn't a professionally made game it's still fair to compare it.
The first thing I didn't like was how it locked up each route. They didn't merge together. It certainly made going back and getting 100% much, much easier it was still very... it rubbed me the wrong way, anyway.
Characters: Some of the characters I liked (Kenji, Emi and Rin being my personal favourite) and some I couldn't stand (such as Shizune and Hisao)... yeah, it's very irritating when you cannot stand the main character. All of the bad endings involve him acting like an ass and they aren't the choices you can control. The one ending where he dies is the best one. Example: he apologies to Lilly after he has an attack because he doesn't take his medication, she tells him not to apologise for his illness... he never expands that he's a dreadfully stupid person.
Naturally, kudos to the writers for all of the other characters - I enjoyed them.
Art: The art is rather nice, some better than others, though Lilly's hand will forever frighten me. When it's close to her mouth... it's... very strange.
Difficulty: This is somewhere in the realms of easy and searching out the bad endings. It's rather irritating going out of your way to find the bad endings just for a hundred percent and this brings me to my biggest problem with the whole game: the skip text speed is too darn slow. When you're searching out all of the bad endings... you've got to sit through everything again and again. Even before then, just going on the separate routes you have to go through Act 1 over and over again. Incredibly boring. Of course, this leads to the magical reason as to why the credits as skippable but to get 100% you shouldn't skip the ending.
Sex scenes: these annoy me. First of all there's a song called "To Become One" which is the worst music to be played over any sex scene. Horrendously cheesy. For the sex themselves - meh. I was horrible awkward in some places where a girl would say "comfort me" and Hisao would just whip off his trousers. Last time I check a hug was enough... this does bring up the fact that Rin does hug you (no CG oddly...) and then later says she can't hug you.
It's the matter of the curate's egg. All the bad things about it ruin it.