I could be wrong, since I've never read the manga, but I did flip through it at a store once. I wanted to figure out if it deviated from the anime at all, and thus for me, if there was a reason I should read the manga. But every page I flipped through was verbatim with how it happened in the anime. So I decided not to get the manga, since I'd rather just watch the anime again. I might be in the minority who feels this way, but I prefer if the anime deviates a little bit from the manga, so I have a reason to read the manga. I'm enjoying reading the Rosario + Vampire manga right now because things happened in a different order in the anime, so they played out somewhat differently, and a lot was skipped over in the anime. Of course, it often makes for a better anime the closer it sticks to the original bron material, especially for something like Death Note, but I do feel a little bad that it causes me not to read the original manga.