Ma no Kakera has stand-alone chapters, with pretty simplistic stories, so don't expect something which will blow you away. Despite that lack of complexity, I didn't find most of the stories really predictable. They usually have a twist, which in some cases will leave you like WTF? (specially Nanakuse Kyokumi and Haunted Wood Mansion stories)
I find Ito Junji's art really great, and Ma no Kakera is not a exception. It fits the story well and creates a proper atmosphere.
The worst part of Ma no Kakera. They have no depth and are completly forgettable. However, being a totally plot-driven manga, the characters aren't
really important to enjoy it, so the lack of characterization doesn't affect the quality of the story.
Despite its flaws, I truly enjoyed this manga. I got hooked on it and I didn't stop reading until I finished it. It certainly is not a masterpiece, but will give you a good time.
If you liked other Ito Junji's works, specially his stand-alone manga, give Ma no Kakera a try. I'm almost sure you'll enjoy it.