The actor explained that, while he personally thinks Harry is a good man, he can understand why others would not feel the same.
"I think he's likable, I think he's awesome," Sommer said to Ology. "But he's more likable to an audience... If you worked with someone like Harry, you might hate him. I hope for the audience to love him."
Sommer went on to say that he has enjoyed the increasing amount of dark humour in Mad Men's fifth season.
"I certainly notice that it's very funny, [but] I think the show is always funny, mostly because me and [John] Slattery have the best lines," the star commented. "I do think the tone shifts throughout the season, it stays funny, but the humour-to-darkness ratio shifts."
Mad Men airs on AMC in the US and on Sky Atlantic in the UK.
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Watch a trailer for the fifth season of Mad Men below: