It seems that every live action derivative of a manga/anime that I've seen has been barely watchable at best.
These movies on the other hand were entertaining to the end. They stayed with the main plot as much as possible and delivered the memorable dramatic scenes with new live action flavor, but changed the plot without opening holes and delivered a new, believable conclusion.
I didn't like Fujiwara much in the lead role- he's not dynamic or conniving enough to bring the role to life. Quite often his face seems to "give it away" when his role calls for a solid and impenetrable exterior.
Matsuyama, however, takes on the ridiculously difficult role of "L" and absolutely rocks. Vocal tones, strange postures and movements, appearance, mannerisms, all breathe life into what was one of the best characters ever to grace manga shelves. My only complaint was the over-decadent manner in which he ate his candy- it seemed a little contrived, as opposed to the more matter-of-fact noshing done by the manga/anime character during his investigations.
Thay certainly could have done a lot worse, and they took enough film time to do the series justice. Can't wait for the American version.