I'll add some constructive criticism, but also a lot of praise, because this game is very much promising and I've got the feeling, that UFO might become really popular for its fresh approach on an erotic sci-fi VN.
I very much like the characters, who are in the game already like Pamela, my absolute favorite, who unfortunately lacks content for the time being. I really hope for a lot more Pamela content in the future.
There is also Aisha and the queen of Terra residing in former L.A. All are awesome and very much promising characters. Just Barbie looks too artificial in my opinion with her doll face. I'd prefer a facial rework for her, making her more realistic looking like Pamela or Aisha. According to the story Barbie is an outdated sex doll robot, which might explain her more artificial and therefore inferior looks somehow. Nevertheless there aren't many pictures in the game, yet, featuring Barbie. So if a rework of Barbie is something the dev would consider, it was best done early, as long the game hasn't that much content, yet. A character rework much later would mean much more work, because of the amount of pictures and scenes, which then needed to be replaced. This very much is the only criticism I have so far, I really like all the characters in the game, just Barbie is too artificial doll face like for my taste. Her erotic potential is therefore capped – she’d be much hotter with a more realistic face. She can still be a inferior sex bot model storywise compared to Pamela, but that doesn't mean that her facial features have to be that much inferior compared to the other more realistic looking characters.
In general the story is hilarious, the dev really has got a good sense of humor and therefore it's super fun to play. UFO got a really lighthearted story for relaxed playing! Well done, dev! I also appreciate that contemporary political references of the very early versions were removed, because it simply isn't advisable to alienate half of your player base. It's much more light-hearted without contemporary political references. Well done!
Furthermore I'm not a fan of alien sex in general. The existing daz models which represent aliens aren't very much appealing to me. Of course it’s a science-fiction setting, so some alien girls are supposed to appear at some point of the story, but I’d advise to keep them humanoid and not making a total freak show out of this game. Anyway this is just my personal opinion and I think the dev really did a superb job so far and I'm confident, that this game will become better and better with each update.