PoP is worth checking out right now, but it still needs some polish and maybe even gameplay changes. The sheer amount of more or less fleshed out game mechanics is enough to make this game interesting, but it is a double-edged sword that can easily overwhelm you.
Still, it seems that the dev is more focused on the gameplay and puts only the necessary amount of time into the presentation (though I don't doubt that the game will have tons of great art later), which is a good approach to a management RPG like this. You can tell that it took a lot of effort to string every mechanic together: there's so much stuff you actually need to do, but none of it feels unnecessary or out of place. Things are still unbalanced, though, the main clue for this being the King's requests that require you to know how to play the game and get lucky with the characters you get, because I don't think you can keep up with his requests otherwise. The requests scale too, so even if you skip one, you are expected to catch up later.
Thankfully, the game lets you toggle freeplay mode or just cheat and continue after failing too many requests.
Other than that, PoP plays fairly well. Both management and RPG features and mechanics are easy to understand, there is no ambiguity in most actions. It's just fun to play the game, breed and fuse the characters at the start, get the gear and go into a portal to feel your way around and figure out what sort of party you're going to have this time. Kinda hurts to get instantly steamrolled sometimes, but more often than that some characters would click together and you would feel like you're on the right track to get a perfect team, which in turn prompts you to breed the characters to get an ideal specimen for a certain role.
The NSFW content is alright, I guess. The sex system is nice, although the "fun" stat it has really confuses me, the artwork is good and it is a nice way to bond with the characters that you like.
But this is clearly a game that focuses more on SFW stuff rather than porn and that's for the best. Similar to (now dead) Breeding Season, the porn and the idea of sex are not the end goal and only reinforce the gameplay. You'll come for the cute monster girls and stay for the hot, hardcore number management.
I guess the only notable downside is the UI. I don't even care that it's raw and that I can see the default Unity font and textfields. It's the fact that it doesn't have good management tools like sorting or filtering for characters that bothers me. Having more than ten characters overall or more than three characters of the same (or even just similar) species can become tedious. This is probably the biggest problem of PoP, because you can't work around it. It messes with the tempo and makes you stop whatever train of thought you had to go through every character and look for the one with the highest stat, only for you to double check because you had three Lizardgirls with the same portrait and you didn't bother to remember their names, so now you have to go through the three of them and, oh shit, what was her name again, and... you get it.
So, overall, Portals of Phereon is on its way to be one of the best NSFW management games. It's clear that the dev has skill and patience to make it even better, though I hope that they will take some time to work on the Quality-of-Life updates for the next versions.