User blog comment:Xilinoc/Ch. 575 - THE KILLERS HIGH/@comment-24153155-20140404002617/@comment-5693502-20140407162249

I would agree with you completely, what he can very much be considered childish and immature. But childish/immature doesn't always equal unintelligent. He might be lacking some common sense, but a reptile brain ? No.

I'm agreeing strongly with your second point (him being immensely powerful compared to other beings) as in my opinion it's more-or-less his reason for not using any brain power. Why bother strategizing against a weaker opponent ? It's like a human strategizing ways on how to defeat an ant or telling Superman to make plans on how to defeat a child in combat; i.e. pointless.

Oh and I meant the cleverest characters are those on par with Mayuri, Urahara and Aizen (who are leagues ahead of everyone else) not that they were the only intelligent characters.