Falling into 6 genres, Sankarea lacked a specific direction and yet remained enjoyable.
The first 3-4 episodes focused on mainly building the setting on which the rest of the show would be based on, and from there it took the direction of a typical romantic comedy SoL type anime. Being a fan of many SoL anime, I found the rest of the show to be enjoyable. Those who do not enjoy SoL shows may be disappointed after watching the well paced, plot based first 3 episodes when the majority of the show is a character based comedy.
As for horror and ecchi, both were incorporated into Sankarea in an unobtrusive manner. Whist the first 3 episodes had horror undertones, the rest featured horror in a more comedic manner. Nothing overdone or such. Ecchi was also incorporated smoothly and presented in a subtle manner. Nothing too distracting and in-your-face yet still enough to provide service to ecchi-fans.
Individual score breakdown
Story: 6
After the first 3 or so episodes, the plot of Sankarea quickly breaks down into something similar to a SoL, with periodic arcs. Nothing really remarkable. Heck, the majority of the anime IS character/comedy based. It's still enjoyable, just don't expect some amazing plot.
Art: 9
The art is simply superb. Not only is the quality excellent, the character design is also well done and each character takes on their own unique art style and appearance. The background is nicely detailed, and the atmosphere and lighting done just right. Animation is smooth as well. After watching the absolutely stunning animation/art of Fate/Zero though, I really can't give Sankarea a 10/10.
Sound: 9
Voice acting is well done and brings out the personalities of all the characters. Background music could be a bit better, but it still integrates into the show quite well. The OP and ED are both excellent. Being an audiophile, I found everything to be recorded nice and squeaky clean.
Character: 7
Other than the story, the character was the second weakest part of the show. Both lead characters were well personified and likeable to some degree. Unfortunately, every character was a subcategory of a cliché, but kept me interested through the rather... unusual circumstances the lead goes through.
Enjoyment: 9
Much of the enjoyment stems from the comedy. Although it is no where as good as the better SoL/Romantic comedy/Comedy I've watched, Sankarea was mostly entertaining.
Overall: 8
I believe Sankarea deserves better than a mediocre 6 or 7. The whole quality of the show is very impressive, and even though the plot and character is slightly weak, I give Sankarea a very good 8/10.