Honestly I understand why people feel underwhelmed by ep9 - I thought so too after finishing my blind playthrough (which happens to be DIK Sage path) and felt a little sad by the same points that the majority of disappointed people highlight - seems underwhelming, not a lot of content compared to ep8, no meaningful plot advancement, too much free roam etc...
So I have replayed the whole game 6 times over the span of several days covering all major branches, and now I appreciate ep9 for what it is - an opening to Season 3.
By now we can all agree that we can trust the good Doctor when it comes to storytelling, and we needed this party tailored to all of the branches for each of them to work when it comes to the bigger picture - yes, that meant less content for a single branch, and it was heart-breaking to see the breakups when you are emotionally invested in each of the relationships across multiple saves, but honestly I feel that people who complain the most just have 1 or 2 saves and did not get to experience all of the content.
Going forwards seeing that we have "cheat" points introduced now, we will see most (or maybe even all/depending on choices?) branches overlap at some stage and from both story and development perspective that makes sense. Will MC feel like crap about cheating? Yes he most certainly will, but that's classic DrPinkCake play on emotions.
Ep8 had everything - character development, plot advancement, relationships advancement (or rather choices and consequences wrap up), plot twists and plenty of sexy content because it was a season finale, that is what it needed to be. Ep12 will be the same, and the brand new journey towards that has just begun. Interlude provided plot advancement (or whatever you wish to call it - it still was a plot heavy release), and now we get the sex focused episode. Ep10 will either be plot focused or balanced for sure (Christmas party will probably be in ep11 or 12 unless it's rushed).
I don't feel disappointed anymore - I feel excited for what's to come - each branch ended on amazingly great cliff-hanger alongside Derek's discovery(the battery in the bug is low, so that's why it was not flashing before and he did not notice it sooner), can't wait to explore them all further!!! ("don't fall in love with me" struck a special chord for me)
That being said even further branching with the new LI girls (that being said who the fuck is that blue-eyed masked girl? very mysterious) might seem like a red flag to development times, but theories aside we shall see the impact of that in ep10 for sure.
In conclusion - don't get your DIK soft, brothers - this is still THE best VN out there. Cheers to the good Doctor!
PS: