It's like a nicely written book with pretty images on top of it. The greatest strength of VNs, for me anyway, it's not just the story but the character interaction and learning one's personality. You wont get to know character anywhere else like you can learn in these types of games (aside from few other gameplay-related Japanese games). From the life important things to unimportant things, all that info gives us insight of a character that we are looking at and it's what makes us love them. The choices during the VN, if there are any, drive us to pick the girl that intrigues us the most, be it by her looks or some moe stuff that she showed. But of course, there are always exceptions, like Down said above...