The former Manchester United and Ipswich midfielder said: "He can create chances for himself, but sometimes he's a little bit selfish. He's not a player who plays a lot of one-twos. He likes to do things on his own.
"Sometimes I don't like his temperament either. He does anything to win games.
"If he has to dive for that and win penalties, he just doesn't care. He was suspended for several games for a biting incident. It's going to be difficult for him to settle."
Speaking on BBC Radio Five Live, Muhren said: "He scored 34 goals in all last season, but I'm not sure he's going to score that amount in England, especially for Liverpool. They don't play very well this year.
"It's going to be more difficult for him at Liverpool because there are many good players there who won't always give him the ball."