Opening Remarks - If you haven't seen Higurashi in its entirety, I strongly recommend that you do so before attempting Umineko. It will help put things in perspective.
Story - Back when Higurashi burst onto the scene, it brutally massacred not only its own cast, but the accepted norms of storytelling in anime. And with its spiritual successor Umineko, we're all justified in expecting more of the same.
Well, yes and no. Umineko is confusing on so many levels, not just its recursive story arcs. Unlike in Higurashi, the cyclical nature of the reality in Umineko is made abundantly clear immediately after the first arc, but instead of clarifying things, it just makes the entire understanding even murkier. One is left wondering if it might not had been better if Studio Deen had simple left it as they had done Higurashi, without bothering to explain the parallel arcs at first. In any case, the metagame scenes involving Battler and Beatrice in their tea party, while visually appealing and with pretty good dialogue, is easily the weakest link in the production because so much of what goes on is inexplicable.
For one thing, the magic employed in the series seems to be very whimsical, arbitrary, capricious and downright contradictory. I can see only two possible reasons why this is so.
1) Studio Deen actually wrked out the entire structure for Umineko's magic beforehand, complete with a set of rules and flavour and all, but deliberately leave out vital details and puzzle pieces of their anime. Whether it is to dazzle and confound the audience or simply to set up a second season (please let there be a second season) remains to be seen.
2) Studio Deen is really a cubicle office full of lazy bastards who are just making up flashy stuff as they go along and using "magic" as a convenient excuse for everything. In which case I'll like to cut the score I gave for Story by half, as well as give all the collective staff of Studio Deen a big fat middle finger.
I'll prefer to assume that Umineko will follow the pattern set by Higurashi, with the relevant answer arcs in the second season, so I'll stick to Case (1) for now.
In any case, the metagame between Battler and Beatrice often ends up on the backseat until the end of each arc when (after everyone's dead) they confront each other again. In the meantime, the anime takes us through a wondrous series of character conflicts, each telling its own story. An unusual and unconventional means of ccharacter development (more onthis later), but it worked spectacularly in Umineko. It allows the audience to follow the occurrences in each arc without getting bored by same-old same-old, and at the same time gives the studio the luxury of exploring (or showing off) other avenues to flesh out the anime.
Umineko's story definitely doesn't go easy on the viewer. Be prepared fora degree of mind screw; if you've seen Higurashi and think Rika was the good guy and Okonogi was the bad guy, then, well, you might be in for a bit of a shock. It takes a bit of focus to keep up with, but thanks to its cyclical nature offers the viewer plenty of time to catch up and figure things out. Not that it gets you very far, the end of the series leaves a bunch of puzzles regarding the nature of magic quite unsolved. But then, just as Higurashi left us all wondering at the end of the first season whether there was any point to the thing at all aside from watching high school kids maniacally clobber each other, perhaps the second season (fingers crossed for a summer release) will offer enlightenment. I'll say go on and give this a try, unless you're one of those snooty high-brow but-they-don't-speak-in-haiku/iambic metre types.
Animation - Gorgeous. The colours are vivid and varied without being outrageous. The lines crisp and clearly defined. The character art, while not being particularly original, breathtaking and making a mockery of previous standards.
Studio Deen has done beatutiful work over the years, and in Umineko they have scaled new peaks in their penmanship. There are some of the familiar maniac faces we know from Higurashi (and our own nightmares), but with freshened touches. In comparison, after watching the anime, looking at the old art from the visual novel might make you cry in horror.
CG is employed, but very sparingly. The faces expressive without being distracting, the costumes stylish and elegant, the backgrounds solidly rendered and varnished. The character art is noteworthy for how every cast member is distinctive in his/her appearance, behaviour, dress sense and mannerisms despite having such a large cast; too many productions try to fit in a cast larger than the creative wellspring of their crew, and it shows (I'm looking at you, Clannad).
Oh, and the gore. Not nearly as terrifying or disturbing as Higurashi, but definitely flashier and aesthetically more enjoyable. Maybe it's just something to do with my stomach turning over at the thought of pulling a fingernail off that impedes me from saying the same about Higurashi, but- OH SHIT STOMACH FULL OF CANDY TURNING OVER AAARRRGGGHHHH *retch*
Sound - I don't think much of the ED, but the OP is a spectacular success. The vocals are stirring, the use of Italian a sublime masterstroke and the accompanying trailer a mad rush of faces employed to brilliant effect. Probably one of the most enjoyable openings I've seen.
But the real star of the show is the voice acting. A host of experienced seiyuu have pitched in to bring the cast to life, and they don't disappoint. Particularly praiseworthy are the various witches: the playful curelty of Beatrice, the sinister aloofness of Bernkastel, the chaotic mischief of Lambadelta, the all-consuming greed of Eva, the vengeful madness of Maria and the depressed indignance of Ange all wonderfully shine through from their voices.
Beatrice's mocking laugh (note that the anime uses the Italian rather than English enunciation for her name, so it's not wrong and stop blasting them for it) may be grating to some, but is quite literally music to my ears. Most of the witches also have multiple personas, and it is an audio feast to hear them switch between roles beautifully. It's like ice cream in your ears, really.
Characters - Many viewers may be tempted to, within the first arc, start ignoring the apparently peripheral characters and start focussing on the core cast. It is an understandable approach, given that the cast of almost 20 regulars may be daunting for those not used to it. But it will also be a terrible mistake, as I expect any Higurashi veteran to know. To discount the 'supporting' cast in Umineko will be like watching the first season of Higurashi with only the scenes of Keiichi and Rena left in.
No one in Umineko is left redundant, and every single cast group comes to the front, if not centre, of the stage at some point. Even the humble servants and summons. Well, except the goats.
I previously mentioned that Studio Deen craftily worked a large number of character conflicts into the story by manipulating the cyclical arcs. The effect is that despite the large cast, the majority get a respectable degree of character development and airtime to investigate their backstories. Every member of the cast becomes a complex figure with a complicated past, many intricately woven either with the island mystery, or more magic. Even those cast members who don't get a chance to tell their story offer tantalising hints that there is much more to them than meets the eye.
A recurring theme in Higurashi then was madness, as the various characters take place being driven to the brink of insanity and brutally murdering other villagers. In Umineko, there is madness as well, but madness is eclipsed by cruelty. Every murderer is shown to be in fairly good control of himself or herself, and far from being mad, is quite lucidly and deliberately working towards a specific goal. They just like to toy with their prey a lot. It may be indicative of Umineko's magic, in a way.
Closing Remarks - I'll end here with these words: PLEASE LET THERE BE A SECOND SEASON!