They are more expensive but the figures I have seen are 3x for Ariane 5 and 2x for Ariane 6 (source : https://spacenexus.us/guide/space-launch-cost-comparison).

Then, it depends on what you need to do. A 3x cost if you deploy a strategic constellation is fine. A 3x cost if you want to launch huge payloads for a Mars trip (I know costs were for LEO, just giving an example) is probably uncompetitive.