Probably the Best VN out there in spite of how short it currently is compared to most VNs. You could have a game like Dark Magic by F.Lord, which goes on for an extremely long time, and it does not match the quality of the story & characters & everything Summer Heat has to offer. What I especially appreciate about this game is how slow paced it chooses to be, opting instead to let you get attached to the characters and all. This is probably the first VN I have ever played that has really made me slow down & read the story throughout all of it, & I love the story. I like how a large sum of the girls, especially the main ones, are quite modest & don't automatically try and prostitute themselves (*Coughs* Cassandra). I noticed in your reply to one of the comments that you plan to add pregnancy, along side marriage & all makes me most excited about the future of this game.
I absolutely love the potential roots you can take with the characters, such as Mia, who matches a more innocent highschool sweetheart. Sophie who seems projected straight to wifehood (according to her answer to the questionnaire), and I absolutely love that. Eve I love as a potential individual the character can invest in to help her come out of her rock (without the requirement of a sexual relationship). And Helen is a really good character to demonstrate the main character's, well, character, by him treating her as an equal in spite of how annoying she is presented. I love all the characters, they are really well written and not all that surface level (*coughs, Mr. Miller*). As a little tidbit of criticism (seeing as I only have praise for this game), Mike is treading a fine line between a gamer & jock, which usually tend to be mutually exclusive. But other than that, very good.
Oh, & the visuals. This is clearly the best looking VN I have ever seen. I would absolutely love to know what program you are using to make these graphics, because they are absolutely fantastic. The characters are well detailed, fairly distinct, and charming in their own way. The eyes, of all things, really do help in immersing you with the characters, and do hit a good sense of realism without being uncanny.
My favorite scene thus far is the scene right after the questionnaire, where the player reflects on the character's answer. Not only does it look absolutely stunning, but it really does help you care about the characters. I also do like the added feature of often times just answering with "...", because sometimes that is just how we feel. Overall, the best VN I have ever played, and will be very much beyond enthused for the next releases!!