The Hoops manager often gets stick for his touchline displays and comes across as an angry man who believes the Scottish football community is against him.
But Shiels, who took the reins at Killie following the departure of new Finland boss Mixu Paatelainen recently, insists that Lennon is simply a man who loves his job and his club and should be allowed to show that.
"I have always had admiration for Neil. Things have happened to him that I think have been unjustified," he said ahead of the clash between the two sides on Wednesday.
"People have said things about Neil that are not true and they don't know the fella. He is a nice guy, an intelligent man who knows his football.
"He is a passionate guy. He loves the game. You can see that he loves football. He takes it to heart if Celtic are not playing well and he lets that passion emanate out and he wears his heart on his sleeve. He is a good guy, Neil.
"He's been in the game for a long time and he is a legend at Celtic. I have nothing but admiration and respect for him but hopefully I can disappoint him on Wednesday night."