Assaidi completed the switch yesterday.
He told liverpoolfc.com: "I am delighted to have signed for this big club. I spoke with the managing director, Ian (Ayre), first when he came to Holland. After we spoke, I had a good feeling. Then I spoke with the coach (Brendan Rodgers) and when I did, he gave me a good feeling. How he wants to play is the way I like to - I want to play football.
"That's what we did in Holland and that's why I had a good feeling about coming to play for this big club. The fans here are great - they make a brilliant atmosphere in the stadium. This is a great club and you can't say 'no' to it.
"I had offers from Galatasaray, Spartak Moscow and Ajax - but as I said before, I had a good feeling after speaking with the coach. When Liverpool come to you and say they want you, you never say no to this big club. I am very happy to be here. I signed today for one of the biggest clubs in the world."