Active Skill knocks out 30% current HP ignoring defense, which used to be extremely useful against bosses but is now out of fashion due to long cooldown. Awoken Evo makes him a formidable Two-Pronged Attack Two-Pronged Attack team member and his active drops 5% but gains a five second time increase for a turn, but his evolution requirements are even harder than the other Roman Gods. If you want to us the regular Ult Evos you will need to skill them up, so you are going to need a lot of Hera, but at that point you would be better off using them for their stat stick, and in the case of Hera-Is, her awokens.
I have two in my box, and they are very low priority.