I doubt Steve Jobs will regard being called monomaniacal as an insult. My dictionary defines the word as 'An inordinate or obsessive zeal or interest in a single thing or subject." That sounds pretty much like the Apple co-founder and CEO.
The comments from Microsoft co-founder Paul Allen came in an interview with The Sunday Times, where he also praised Apple's almost unbelievable turnaround since Jobs returned to the company in 1997. The full article is behind a paywall, but the Guardian quotes it here.
There's a lot more of interest in Allen's recently-published autobiography, Idea Man. One passage from the book that will make Apple fans take notice is this one quoting Bill Gates in the mid-nineties:
"[The competition] can be taken. But the only way we're going to take them is to study them, know what they know, do what they do, watch them, watch them, watch them. Look for every angle, stay on their shoulders, clone them, take every one of their good ideas and make it one of our good ideas."