Finished yesterday. My hot takes:

chapter 3
>well-presented but a bit too gimmicky
>gameplay variety is pretty good, quality of ch 2/3/4 make Undertale and ch 1 hard to go back to
>the method for fighting the "secret boss" is horseshit and way more obscure than the previous two chapters, had to restart and do the entire chapter again
>"secret boss" itself is kind of a fun challenge but the game is leaning too hard into violence
>Tenna is a fun lovable character but not very funny (maybe intentional)
>Roulxs Kaard is the best character in the game
>Toriel not having an active role in the story is disappointing
>Knight's identity is too obvious given the available information, if they stay the main antagonist the story will lose juice

chapter 4
>less gimmicky and more exploration focused which is good
>no villain-of-the-day makes the chapter feel empty (I guess it's due to the tonal shift)
>likewise no Roulxs Kaard fight because of tone
>while ch 3 and 4 each have a good amount of content in their own right, the way they're written/paced makes them feel like two halves of one chapter
>Titan fight is kinda lame, doesn't really have any twists to it, and it's another forced violence fight - really hope the rest of the game isn't like this
>secret boss is great, nice change of pace and isn't walkthrough-bait

Overall pretty enjoyable experiences but not perfect.
Chapter 2 is still my favorite.