Signs help *A LOT*. At first it didn't occur to me to use them because in the original Witcher I never put points into it. But since you start with a low level version of each spell in this one, they seem to have designed the combat around you using them.

Traps, mind control, the damage absorbing spell, aard aka force push, etc. It does seem a little weird to have to treat every fight against 3 or more low level guys as a boss fight, but that's what you gotta do.