So, since making this thread I've played several of the routes, so I'm coming back to the discussion to comment-
They are typical anime boys in terms of looks, but definitely appealing. I may be biased because I prefer bishonen- but even so. I do think Zen's art is drawn exceptionally, so I'll share a couple. I'll put the pics in spoilers since they're quite large:
It's not your average dating sim, the characters are interesting and so is the story. I recommend it as worth playing, although I agree with Triste, it's difficult to play through if you can't afford to spend money on it. The chatrooms open at certain times throughout the day, according to your timezone, so that it feels like you're living your day alongside the characters. If you miss a chatroom, as in if the next chatroom opens (usually an hour or two later) before you play it, it's locked and you have to unlock it. And if you go on to the next day without finishing the previous day's chats, those chats can't be unlocked.
There are guides online for info on when the chatrooms open on each day, but it's troublesome to do every chatroom before the next one opens. I was able to do it because I started playing the game during my summer holidays. (I have three routes left and I'm nearing the end of my holidays, so I'm going to finish the game the next time I have a long break from college.) Also because I could buy some hourglasses.