I'm playing on normal and I don't think it's that hard. You have to make sure you have decent protection and weapons, and you invest in decent abilities. Also, you need to make sure you are actually attacking something, and not just hitting air. This game has a slight problem when you are not using the tactical view when attacking. Your character can hit at nothing. Make sure you are locking onto targets to help prevent this.
Flanking is always good as well as having some ranged attacks from your party. Use your fighters/dual weapon rogues to attack the strong people (two on 1 strategy) and then use the others as ranged (arrow and/or mage) support. Winter's Grasp is good at holding an enemy back and you can shatter them once frozen.