Let me preface this by saying that I'm not a SC34 "stan" by any means. To me it's a game that's good in comparison to the tons of bad and few great games out there. The first episodes were really grindy, some episodes barely had fappable content, and sometimes it just happens that a given episode doesn't have kinks that do something for you (like in my case big boobs or lactation don't do anything for me, so one or two episodes didn't even get me hard). It having not much of a gameplay and the delays between eps don't count as cons to me. On the upside, there's all those virtues that are usually mentioned here: art is good especially for 2D CG lovers, writing is above that of most games, it has humor that actually works most of the time, characters with actual personality and some level of development too, etc.
But I think another good trait of SC34 that a lot of people don't seem to realize is the power of its particular buildup and slow burn. Some long games already have that, obviously: game's long, you get used to the characters, develop some kind of affective bond to them (be it pure or wicked, whatever, what matters is that it boosts the arousal you get in the end), and that gives it added value. I usually finish a game in one or a couple days. But in the case of SC34, because of this "3 years old and ongoing" stuff that some users have been decrying here, it's kind of a double buildup. Buildup in terms of game time, and buildup in terms of IRL time that the characters have been with us. I've played a lot of parody adult games but they don't leave as big of a mark affectively speaking as SC34. It's not like now I see Ahsoka differently now after playing Orange Trainer. I was just immersed in that game a couple of days and that's it. But I realized like half a year ago that in my mind Jasmine is no longer Disney's Jasmine, but Akabur's Jasmine, and more or less the same happens with the other characters. It's like the game actually makes me feel I have a harem of girls with actual personalities too, and the slow burn of corrupting them boosts my arousal when something actually happens. In contrast, some short games offer you explicit CG from minute one, but unless it's very well written or builds a particular fantasy really well, it usually doesn't do much for me.
There's other long-running games, like Something Unlimited for example, but those usually don't slowly develop characters update by update but focus on one character with each update. While it makes for some very exciting stories on its own way, it doesn't make me get as attached to those parody versions of the characters as I am to Akabur's ones, since by the time the next SI update comes, it doesn't do much to strenghten whatever perverted bond with a girl it set up in a previous update. (It's still a great game, don't get me wrong)
I guess what I'm trying to say is that, in my personal experience, SC34 does a good job of actually making you feel the harem fantasy by making you get attached with the characters through the years. They make their own space in your mind, while the ones from other games kind of fade.