When I first grabbed this I thought, "Oh this will be a nice slice of life," and oh how I was wrong, but ignoring that I remembered a friend of mine mentioning it was beautifully terrible after I decided to watch.
School Days is quite beautiful when it comes to the art style and the intro and outro music tracks and the story itself is fairly relateable to most boys or guys that have gone through high school. The story is not terrible considering that it's following the life of a fairly normal introverted high school boy that comes out of his shell. I think this anime took the story to extremes that made it a little more difficult to relate to but the characters are generally introduced fairly well and you are told what you need to know about them for it to make sense.
Watching this I felt as though all the characters were in a perpetual state of intoxication and I don't mean tipsy I mean full on black out drunk but the character interaction is about as normal as you can expect given that everyone just does what ever they want.
School Days does do a good job of showing what high school students would do in the given situation and speaking from experience I can say the relationships are fairly realistic considering the above that everyone is drunk.
As for a reason to watch School Days I would say the twist the end is definitely worth watching through the story for, however you could get away with watching the first two episodes and the last two or three and you'll pretty much follow the entire story. If you have issue getting through the first episode I will say it will not get any better for you, it will most certainly go down hill very quickly. If you develop any emotional attachment to any of the characters you will almost immediately have a bad time.
TL:DR
Do not watch this if you are looking for a "feel good" anime. If you can't handle the first episode it will go down hill very quickly. If you pick a "best girl" and get attached you will immediately regret it, but bright side being there are so many options for best girl. Personally I think the twist at the end is a minor twist in comparison to the twist just before that one. This is definitely worth a watch if you are a bad person and occasionally need to feel bad.
TL:DR
