Hillside is the most slow-burn AVN I've played to date, and players who want to get to the lewd stuff right away are doubtlessly going to end up frustrated -- but the story is solid and the renders are beautiful.
The renders and character designs in this game are great, and all the characters have interesting backstories, complex personalities, and their own motivation. The narrative head-hops from one character to another, which might not be to everyone's taste, but I found it really deepened the understanding of the characters.
There is also a lot of low-key tension in the story. It gets borderline comical how often in this game a character will go from trusting the MC, to totally distrusting them, and back again, particularly Charlotte, who can't seem to figure out how she feels about MC no matter what. I found this added a lot of fun to the story.
My only real issue is that Emma as a character is meant to be 18 and in college, but that quickly falls apart under scrutiny. She's extremely naive and her "college" is very clearly a high school. The story surrounding her starts out relatively wholesome, but it's obvious she is moving toward LI territory, which could be distasteful to some players.
Not exactly a "con," but the environments in Hillside are generally very limited. A great deal of the game involves the three main characters in the house knocking on doors and checking on each other. This isn't necessarily a bad thing, as it allows for a more interesting story, but if you dislike lots of long conversations in living rooms and kitchens, this game might annoy you.
Overall, I had a lot of fun with it. Gorgeous game to look at, largely wholesome story. A good time but unlikely to be an all-time favorite.