I haven't seen such a bad manga in a while. There are several reasons for this, but lets start from the most obvious:
1. Title is a lie. MC is called a healer and all his powers have "healing" in name, but they neither use healing effect, nor are linked in any way to healing. If in RPG you could imagine someone killing enemy with some kind of overheal or overgrowth, but here you should try to imagine something similar to "healing fireball". Sounds bad, doesn't it?
2. Story. It should be a usual "bad guys did bad things to me, so now I will have my revenge" type of plot. The problem here is that instead of moving to his goal MC starts gathering his harem from the start. Not only that, but the list of bad people for his revenge is so vast, that includes basically everyone who is not in his harem or at least has some link to his harem (like friends of his girls).
3. Characters/World. And why, you ask me, is this list of bad people so big? That is just because author, instead of trying to paint at least somewhat believable picture of a fantasy world with average joe being just a guy who works a farm for living, decided to make some kind of "MC may be bad, but everyone around him is worse, so whatever MC does is totally justified" world. And, just to fit this world, every single character that is against MC is just as edgy and evil as he could get, with no redeeming qualities at all. And, speaking of MC and his party, you will not find any personalities either: harem is just harem for sex, MC is stupidly overpowered with a set of cheating abilities for every situation and just does what he wants. And what does he want?
4. Sex. Yes, I will put it in a separate paragraph, just to give this topic as much focus, as the author does. Oh boy, it is everywhere. After reading all the chapters that were available, I could not get rid of impression that I read a cheap hentai. And in a cheap attempt to hide his wish-fullfillment dreams of sex author makes a "sex levels you up (if it is with MC or other heroes)" rule in this world. That's why everyone wants to have their way with MC, that's why MC uses it to power up his harem, that's why it is so hard to find a chapter where there is no sex.
5. Art. And to make it clear, what this manga is for, the only more-or-less decently drawn scenes in this manga are all for sex. Outside of this art is nearly non-existant, battles end in one swing/explosion, so no art here, all characters have one expression glued to their faces, so no art here either, backgrounds are just there so nothing special here too.

Enjoyment from this manga? Well, I must admit, at some point it became so bad that it started to be hilarious, but I can't really say that I had any enjoyment from this series.