In Umineko no Naku Koro ni, the members of the Ushiromiya family gather on the island of Rokkenjima over who will inherit the family wealth and power with the impending death of Ushiromiya Kinzo, the head of the family. However, someone or something starts killing them off in gruesome ways until none are left alive. And then they are killed again, and again, and again …
Like Higurashi no Naku Koro ni, Umineko no Naku Koro ni screws around with your head, and you’re never quite sure if what you’re watching is real or not. It does give a much stronger feeling that there is a logical puzzle to be solved, and it can make you want to speculate endlessly on what is really going on (and no doubt most of the speculations will be wrong). For those who like their heads being messed with, without getting the feeling that the story is just an incoherent mess, this is great. It may or may not help that there are rivers of blood flowing from the gruesome deaths that occur.
Umineko no Naku Koro ni is actually based on a visual novel (basically a novel you read on a computer) that is still being released episode by episode, so the anime has only shown about half of the overall story. Only the question arcs have been animated, which basically shows what happens but not the mystery behind them, and it will be a few years before the answer arcs can be animated (if ever), since the visual novel has to be completed first. I really look forward to the sequel, and hope it is indeed produced.
Those that have read the visual novel will probably rail about how much is missing from the anime adaptation. As someone who hasn’t read the visual novel but have heard a bit about the source material, I think a completely faithful adaptation would have been a endlessly dragging disaster. However, that does not mean that the adaptation could have definitely been done much better. And given how small things might potentially be huge hints in a show like this, the small mistakes here and there are not so good.
If you have a lot of time and love trying to figure out mysteries, then I would definitely recommend that you read the visual novel (which is something I would like to do one day). If you don’t have the time, however, the anime would be an adequate substitute to whet your appetite (and personally, however superior the visual novel might be in other ways, I much prefer the character designs of the anime). However, if you only like straightforward stories or want answers right away, you have to keep away from Umineko no Naku Koro ni.