Very intelligent, had all sorts of ideas, could talk about anything related to his field (networking) and would challenge you to think about things differently. Unfortunately, he could talk all around theory, but he couldn't execute. It was a strange sort of inability to choose between several equally good approaches to solving a problem. Every project he worked on got about 3/4 to completion and then fell flat into failure.
Almost textbook description of ADHD. ref: http://news.ycombinator.com/item?id=2877100