Ed Noon is the most bizarrely evolving protagonist I've ever read. Ed McBain and John McDonald both frequently tempered their long-running characters to fit the times, but neither Steve Carella nor Travis McGee can hold a candle to the bizarre biography of Ed Noon.
Noon begins as a fast-talking private eye in the Big City (Philip Marlowe, and others). His investigations then turn a bit trickier, and more 'clever' (87th Precinct). But not for long, because then the President calls. Noon solves a few quick cases the President's current 'fixer' (Chester Drum) - which turn increasingly into pan-European, anti-Communist sex-romps, showcasing the latest in espionage gadgetry (James Bond). As complicated as that sounds, it still pales in comparison to the 1980's, when Ed Noon fought off an alien invasion (?!).
The interesting thing, at least, judging by the half dozen Ed Noon books I've managed to consume... none of them are very good*. The light-hearted moments are fun, but Avallone consistently attempts (and fails) to give the novels some much-needed depth. Noon isn't a captivating character - he's a stereotype. Even worse, he's a different stereotype in every book, so he's both unempathetic and inconsistent. This lack of emotional connection is what separates Noon from the characters that he's imitating - Marlowe was a wise-cracking misogynist too, but the reader cares about him. Steve Carella and his team solve a lot of very tricky mysteries - but they're also interesting as people.
The Ed Noon novels are talented imitations, but lack the heart to be successful in their own right.
*"None" is a little harsh. The Bedroom Bolero, for example, was pretty good. It is one of the most Chandler-esque of Ed Noon's early period, and has quite a bit to offer as a stand-alone mystery.