To be honest I do not want to go into full detail so I will give you the main concepts.
Story & Development: Rather intriguing but does feel rather cramped up considering it is only 4 episode OVA. Not much development cause lets be honest, it's called "Corpse Party" but there motives are really interesting to watch.
Gore: I love gore anime and this was the icing on the cake. This will make you feel very uneasy and weak if you can only handle mild gore cause this is beyond overboard and I like that kind of stuff.
Art: Was very glad to notice how good it was, can't give any poor judgement.
My Overall: 9
This anime is something I will watch again in the future.