v1.06: If you liked the anime, I feel you'll like the game. Even if you haven't seen the anime, Knight of Erin has plenty to offer and doesn't overstay its welcome. It's about 2 hours long with solid combat, plenty of scenes, a couple of outfits, and some good humor. The protagonist generally has a "well, I guess there's no helping it" attitude towards sex, which is a nice change from the more-common naive or turbo slut archetypes.
Visuals/Lewds/Gallery: Based on my admittedly-limited experience I tend to expect WolfRPG games to have a bit more polish than RPGM games, and Knight of Erin certainly delivers. The gallery is available from the start in the in-game menu and you don't have to trigger sex-combat scenes in order to unlock them in the gallery. All CGs also have hints as to how to unlock them, but none have particularly esoteric unlocking conditions in the first place. You can view the whole scene or just the pictures. Battle-sex is animated and there a few enemy types.
Combat: Win or lose, combat tends to be quick, typically lasting 1-3 rounds. Instead of equipping gear you equip skills: sword skill, gun skill, and two support skills. There's also an outfit slot, but that usually doesn't effect combat. If Erin has gone too long without sex she gets debuffed, but you can initiate sex with enemies (and even KO them if you're good at timed button presses) to remove the debuff and get a temporary buff. The battle system gives you some options as to how the play the game, though you can also just stack attack and crunch through battles while healing outside of battle if you don't really want to deal with it.
Anime vs Game: Erin is even sexier here, with a little less up top and even more down below. Many of the core scenes are covered in each version. The anime extends some scenes and shows more of the male characters' bodeis, while the game has more scenes and more monster sex. They're both well worth your time, and if you liked one I think you'll like the other. The plot (what little there is) is clearer in the game and gives Erin a bit more backstory. The game feels sort of like a side quest in a grander adventure, so I hope we get Knight of Erin 2 at some point.