It confirms in the 'How to Read' files that Mello is, indeed, more intelligent than Near, but his "emotions" hinder him from being on top. Mello was selfish, immature, and impulsive, but in the end, he did the right thing by helping Near, knowing that defeating Kira was truly the main priority.

i like Near more but i agree another note makes it obvious that Mello is smarter...