As much as I want to give this a 5/5 star rating, and go into depth about its individual flaws and boons, it would be completely biased and unfair. I greatly enjoyed my time with this game, but the majority of that enjoyment was derived from my enjoyment of text-based smut, and the many fetishes contained within. In reality, I found this game's combat and grinding to be incredibly tedious, which is unfortunately the majority of your time in this game in general. In terms of smut, though, Demoneater really does hold its own, as long as you're into it. It focuses a lot on vore, hyper, musk, and even some mentions of breeding/mpreg, so if you find yourself turned on by any of that, I can't recommend it more -- as long as you're able to put up with the combat.
Additionally, it even has a bit of content to sate us straighter folk, which I genuinely appreciate. It shows that the dev's willing to feed a bit beyond the m/m audience, and it's a treat. Decent furry text games like this, especially ones that contain such fetishes, are a pain in the ass to find. I can only encourage the dev to further work on this game because, despite its flaws, it can be quite enjoyable.

So, in conclusion, give this game a shot if you're an avid enjoyer of kinky smut, and patient enough to handle its combat. It'll be a pain, but it does have some good gold, once you dig through the tedium. 

UPDATE: DON'T BOTHER. The dev's completely abandoned any development, and hasn't put forward any effort to fix the god awful balancing. Whatever potential this game had's been completely squandered. I'm extremely disappointed.