Is is better to split the rating into a more detailed view?
I've thought about rating for arts and rating for story which can then sum up as the overall rating.

And adding an analysis to split the overall ratings into two groups: before and after completing the series. As I guess some people may be giving a higher score to attract scanners' attention, so the rating Before completion may tend to be higher.

Quote from megane007

IAnd adding an analysis to split the overall ratings into two groups: before and after completing the series. As I guess some people may be giving a higher score to attract scanners' attention, so the rating Before completion may tend to be higher.

No that's because the ratings are biased. You will give something you just read a perfect rating, thinking this is truly the best of the best, but realize later that it is not that great or you are pissed and just rate it the lowest possible score. The many 10's would still dominate the rating. About the ongoing-completed thing, people normally reduce the rating when the ending is messed up, and keep it if it is good, sounds about right.

You can also get this information (art, plot, characters, flow) by reading the reviews/comments.
This also sounds like a lot of work...

in need of romance?
uncommon, sad, sweet

Quote from Lorska

No that's because the ratings are biased. You will give something you just read a perfect rating, thinking this is truly the best of the best, but realize later that it is not that great or you are pissed and just rate it the lowest possible score. The many 10's would still dominate the rating. Ab ...

I'm talking about showing rating in 2 ways
In the database, users already inputted they are reading or finished the series
That won't cause any bias but more clarity of information instead.
(Anyway, ratings are always in bias in anime/manga/game as they are subjective)

With SQL, you can pull out the 2 sets of ratings in 2 separate queries
One with users completed the series; Another with users still reading
And display them separately; that part shouldn't be too much work,
It's true it need more work.

As for the other part, breaking up the score into a few more fields allow the presentation of data in a more interesting way. For example the pentagon/hexagon graphics commonly used in games. That may need more works indeed but it can make the page both more informative and attractive. Anyway it's just a suggestion here.

Reviews often consist of spoilers. For people who are looking for something to read or just brief introductory information, it's better NOT to read any reviews (and don't go deep in Wikipedia).