David Moyes says he made the 'wrong choice' in joining Sunderland last summer.
Moyes has been out of work since resigning from his post on Wearside at the end of last season, and has been given a chance to relaunch his career at West Ham.
The Scot has agreed a deal to manage the Hammers until the end of the season, and has vowed to show what 'he is really like.'
He told talkSport: "Everybody has opinions. I have opinions when I go to watch teams and games as well. Everyone is entitled to that. I think my record would stand up to most.
"I have only managed five clubs in my career. I could probably give you reasons for most of them. The most recent one [at Sunderland] was the wrong choice by me.
"Hopefully, I will show everybody what I am really like. I have probably got one of the best win records in the Premier League."
He has been backed to succeed by former Black Cats and West Ham boss Sam Allardyce, who says that he will inherit a higher calibre of player in the capital.
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He told the Evening Standard: "No disrespect to Sunderland but the quality of players at West Ham across the board is much better.
"From what I have seen there are goals in their team.
"For me, David has a good enough base there but just has to get the team working the right way. He will have a lot of players from which to pick. He will work hard with those players to find solutions to the problems.
"David knows exactly what it’s about in the Premier League. He had a bad time at Sunderland but that will be his driving force to go to West Ham and prove to everyone there - and himself - what a good manager he still is," he added.
"I believe it is a great challenge for him and that inner drive and determination that he has always had will ultimately prove to be a success for himself and West Ham.
"At the end of the day the results will decide what the fans feel about the manager of the club they support. West Ham need an experienced manager in the position they are in. He’s a very good coach, very organised with his staff and he knows what it’s all about."