So, I just started playing(actually, reading) this series. I'm now on #5, going in order of creation. I figured since there isn't a discussion about them here, there should be!
I know Yuri Project has some of the newer ones in translation. Can't wait for their English patches!
As for the games... I honestly didn't know that much about them. I had figured they featured sex occasionally, given that I saw the MaixReo OVA, but since these are the first visual novels I've played, I am not familiar with the mechanics. They have a lot more sex than I expected.
As for the games themselves... So far of the couples I've seen I have a high preference for MaixReo. I love Mai's personality, and also adore tsunderes. YuunaxNanami is great too, love the personality gap there. I was not a fan of the KaedexSara games, however. I didn't like their personalities, and they seemed pretty stale to me.
As a lesbian, I was a little worried that the series would be way too male-centric ero-game in content. Surprisingly not the case. Clearly sex driven, but the relationships are cute and there is nothing too offensively inaccurate in the reading. I enjoyed them a lot more than I thought I would, so I'm glad I gave them a chance. There were some negatives to them, but they aren't strong enough to make playing them a bad experience.
Has anyone else here played them? I'm definitely a fan of the series now and intend to play all of them, for better or worse.