(Edited for Day 4)
The Good-
Awesome premise: hits me right in the fetish!
Pretty strong dialogue. Some humor and good hypnotic induction. Dialogue during sexual situations seems rushed, but not bad. Too wordy later in the story.
Good art! But there should be a lot more of it, given the time between releases. Day 4 looks a bit different stylistically. I could be accustomed to previous days, but faces weren't as appealing.
The Bad-
Story Pacing: Mom and sisters transform over a period of 5 days, so there's not much time for slow, delicious corruption. (I admit this is a personal preference).
Day 4 is a departure because there's lots of lesbianism (not a bad thing) but very little foreshadowing.
Slow development time: There is a consistently long period between updates. (5-6 months is twice what it should be)
VA: It's not exactly bad, I guess. But the VA work didn't add anything for me personally. The younger sister's voice is the only one that is an actual turn-off. And there's volume control.
Overall- I have to downgrade this to Good. I really want to like the dev and have been a supporter in the past. It is worth supporting (sporadically), downloading and playing if hypnotism and incest are your thing. However, you'll be best served by waiting until the whole game is finished and released (if you can).