The 24-year-old was recently named Everton's player of the month for March following a string of impressive performances.
"He's a good player Seamus and he has improved," explained Moyes to evertonfc.com. "The biggest thing about Seamus is that he is a great boy to work with. He is someone who has no edge to him because of his background.
"He played in the Irish league and it's a big step up to come and play in the Premier League. He is thankful for everything he gets and he plays that way.
"He takes it really seriously and wants to do well. He's got good role models in Phil Neville and Tony Hibbert."