Dude is CLEARLY a fucking killer, but school me on him...
When did people start calling him the best and why?
His best wins are?
How do you rate him against the other greats at his weight (past and present)?
Is he still in his prime?
Biggest threats to him at the moment?
Best Boxing of all time at his weight (his hands and head movement are unreal for a KB'er)?
Petrosyan is just incredible. Start here and vote up Jack Slack for his work:
http://www.mixedmartialarts.com/mma.cfm?go=forum_framed.posts&forum=1&thread=2130805&page=1&pc=50
Also check out this thread:
"71 Wins (33 (T)KO's, 37 decisions), 1 Loss, 2 Draw "
http://www.mixedmartialarts.com/mma.cfm?go=forum_framed.posts&forum=1&thread=2023908&page=1&pc=216
He's the most technically sound kickboxer I've ever seen- they call him the surgeon for a reason. 
^ the doctor....my bad
I think they should call him the neurologist
Yep I agree. The doctor is a bit generic for a fighter of his caliber.
Up!
Giorgio Petrosi is the greatest Italian striker today. He is without peer in kickboxing. A true master like Leonardo, Donatello, Raphael and Michaelangelo
So you're comparing him to Ninja Turtles or artists Bobby?
Who is his master splinter. 
sub'd seen one or two fights and.i was in awe, been meaning.to.get more into kickboxing.
J2C1 -So you're comparing him to Ninja Turtles or artists Bobby?
Why not both?
Amazing fighter. Amazing footwork. Simple combos that land. he'll throw the same hook/cross combo for a full minute and land most of them because of his footwork. He seems like an extremely focused guy. I'd like to see him fight in full rules Muay Thai, since some of the guys that he fights are used to those rules and have to adapt when they go to fight him in Glory/K-1/etc. I don't think it would be as pretty of a fight, though.
I think his biggest threat WAS Buakaw when he was in his prime. They fought to a draw, but a lot of supporters think that their guy got screwed. I don't think there's currently a real threat at his weight that fights exclusively under the rule set that he's used to.
Enjoy watching him while you can. Guys like him don't come around too often.
Sub.
No matches for him in kickboxing, needs to do full thai rules!
He's incredible. He's beaten the best guys the weight class has to offer. Not the most exciting guy but definitely the most technical. Fucking incredible to watch how he shuts down everyone.