The former West Brom boss took over from Sammy Lee, who had struggled at the Reebok Stadium having replaced the hugely popular Sam Allardyce earlier in 2007.
And Megson told Football Focus: "The football club is in a lot better state now than it was when I arrived.
"They seem to think it was tantamount to taking over at Real Madrid and then it not going too well.
"That place was in a huge mess and most people didn't realise it."
Asked about the difficulty in filling Allardyce's shoes, Megson added: "I'm not being critical of Sammy Lee, he's a terrific guy.
"But he would have had problems as well because Sam did a really good job at Bolton. They weren't always in Europe - I think it happened twice in maybe seven or eight years - but there were things that needed changing.
"The playing squad was probably the oldest in the Premier League and needed to change.
"I think 34 players left the football club and of the 34 I think there's only two currently playing Premier League football, so obviously other people didn't feel they were good enough.
"But it's a fantastic football club, don't get me wrong. It's a really attractive job for whoever goes in there.
"The only thing that is a negative is that it is also the lowest-spending team in the Premier League."