Dzeko has struggled in his first few games with City but McClaren has urged fans to be patient as the Bosnian has plenty of scope to improve and adapt before he starts to bang in goals like he did in Germany.
And McClaren also picked out his former Middlesbrough player Viduka as a player Dzeko is very much like.
"City have got an excellent bargain in Edin," said McClaren.
"People might say it was £27m, but look at the facts. Just a couple of weeks later, Andy Carroll went for £35m. So maybe it wasn't such bad business after all.
"He's very good technically and has very good feet. In some ways he reminds me of a much taller Mark Viduka. Mark was so brilliant in the box and for such a big guy he had amazing technical skills. Edin is very much the same.
"Given that Edin is a lot taller than Mark, I reckon that his physical presence will be a lot more telling in the Premier League."
McClaren also said that Dzeko may take until next season to really settle and that City fans may have to wait before they see his best.
"I think that Edin, once he learns to settle in England and adapts to the English system, will be a major force, certainly amongst the strikers. He has all the attributes to be a hit in England."