As a game, it's a fairly straightforward turn-based RPG. Gameplay-wise, it gives you what you'd expect - combat and levelling are all quite conventional, and you can buy upgrades for characters with the items you collect.
In fact; as of this writing, the gameplay is actually a bit bare bones. There is a shop, but it hasn't been implemented yet. The characters have mana points, but they don't actually use them so far. There are no healing items or anything yet. In fact, there's not even an option for using items or anything during combat; the only thing you can do during combat is pick which attack you want to use. But none of this really causes any problems in-game, though - everything about combat that *has* been implemented so far works as it should. The only thing I felt was lacking was an option to flee from a battle.
The game is also not too grindy. Early on, you will need to replay the same level a few times before your characters are strong enough to progress. But that's it. Becoming overleveled is possible, but that takes effort.
It also appears that the game mechanics are still going to be fleshed out in future updates, so I'm not worried.
As for game's art, though... now this is where Guild Project really shines. The art is slick, professional, and frankly just amazing. The characters - enemies and protagonists alike - are cute and well-designed.
The number of characters (enemies included) is small, but most characters already have sex scenes. All of the protagonists have implemented nude scenes, and several protagonists and most enemies have implemented sex scenes. There's also an in-game gallery for the enemies' sex scenes, which can be unlocked with crystals that you get from defeating the corresponding enemies.
The quality of these sex scenes is pretty much perfect. Their content is varied, too; several lesbian scenes, several straight scenes, and some masturbation scenes. The only (minor) drawback is that there's little story leading up to the scenes (none in case of the enemies).
On that note: the game's story in general is nothing special, really. It's enough to give a little flavour to the protagonists and the events of the game, but that's it. It's pleasant and mildly entertaining - but while there is some lore and foreshadowing, this is still not a game you play for the story.
All in all, I'd say that this is a pretty good game. I certainly will be watching this one.