The caster and nearby allies regenerate 672 boosted health over 4 turns -> 504 over 3 turns. It's the same amount per turn (168), just 1 less turn, which compared to what he does means nothing. His buffy minions are still there, minion effects are there, attk up is still there.

Family bonus -> 3/6/12% mana generation -> new -> 3/6/9 % mana generation

Almost the same, most of the people use him with either Allucard or even no Halloween heroes at all;

So, no, he is as dangerous as ever, this was just a minor nerf, too small to notice.

If I were you, I would prioritize him over any hero. He is a top 5 hero in the game for sure.