@vikas: For example:
One movie can have 100 reviews, all in the area of 60-70. The metacritic score will be 65.
Another movie also has 100 reviews, but the scores go from 15 at the lowest to a few solid 100's. The average is also 65.
Are those two movies comparable?
No. The first is probably an OK movie that nobody hates, but nobody really thinks is great either.
The second is a you love it or you hate it affair, with lots of fans and haters.