My biggest complaint with SoS 1 was how you could completely avoid the NTR if you didn't interact with any of the events... and even if you did, you could just spend most of your time with her, and go look for memories during some of her safer times, or even then, the first stages with other guys were usually pretty tame. Also that you couldn't really "break up" the moments when they occured... you just either avoided them by having her with you, or were too late to stop them. That is what I like about Nebel over SoS.
What I really enjoyed about SoS however, was that each route felt unique and most didn't feel like purely NTR. Hallf the routes seemed to be more "other dudes took their swing before the MC and they hit while he hesitated."
I also liked how nearly every scene had something the MC could walk up on and get a glimpse or hint with sounds or shadows. Nebel could have used more of those.
I don't like the premise both of those games use - the MC and the girl aren't really dating like a normal couple - i.e. spend time together, kiss, have sex, etc. The MC isn't losing fair and square to someone who's better at sex (as you lose the girl even before sleeping with her), you as a player don't develop the real feeling of "being with that girl", and thus the netorare isn't that strong when it happens. This is why I totally loved the previous game of the developer, where there're full-fledged scenes between the MC and his girl and where, if you avoid NTR, it still counts as a decent h-game with multiple sex scenes. That's probably a Japanese thing where 30% of 30-year-olds are still virgins according to the statistics, perhaps people there can date for months without actually being intimate with each other (I don't even necessarily talk about sex, I didn't sleep with my first gf for half a year when we were 15, but we made out BEFORE starting dating)?
That "other dudes took the swing while MC hesitated" stuff in SoS makes it hard to believe that the girl loved the protagonist-kun in the first place, otherwise she wouldn't have been this easy when there wasn't even rape or psychological pressure involved. Also, I prefer for ntr dudes to be decently looking, the artist of SoS totally loves them make ugly AF (only two dudes were decently looking in SoS and that's already a big step forward from the developer's other games where every male is hideous).
Overall, I think that in terms of ntr and sex scenes this game is a downgrade from the previous game, and as it can be seen from the comments the upgrades to the gameplay were unnecessary even though the author really tried to make something original in terms of it and add actual storyline with plot.
