Okay, I finally have a bit of a thought for this.
Personally (or to a lot of people I guess), what makes a good first episode is that it serves both as a set-up and as a hook at the same time. Meaning, a first episode lays down the elements of the story that which the following episodes will base itself from and gives the sense of what the story is all about, while getting the audience’s attention to look forward for the rest of the episodes. Of course that would mean giving away the story without giving away too much.
And personally, I think Rewrite shows to be an example of this, but for the most part, more so on the set-up side than the hook side. Because the original story is incredibly massive and convoluted with a lot of elements placed in the story, the episode inevitably carried a lot of content to show us the massiveness of the story. And at what expense? So many things were happening in a single episode that some people felt overwhelmed by it.
I’ve also read discussions outside Kaza regarding the episode, and the general (negative) comments is that:(1) it was rushed, and (2) the characters felt stereotypical. I’ve already explained why (1) was the case, but here’s for the (2). I do understand why some people feel this way: Because they jam-packed everything in a single episode, they weren’t able to show enough of the heroines to be able to get any substantial personalities from them. (but heyyyy Kotori’s introduction to the story is already pretty good, I couldn’t ask for more for this episode)
However, I think it’s unreasonably early to conclude that they’re stereotypical. I don’t think there’s anything inherently wrong with archetypes; heck my personality in real life falls on the dandere archetype at first impression. It only becomes wrong when the archetype is all there is, but again, it’s still like Episode 1, and there’s still room for fleshing out the cast.
Also, the thing about Chihaya being deredere suddenly, it does feel a bit fast, but there is an explanation for it. Chihaya is practically (not really so much of a spoiler, but it’s an insight from the VN) just a weird combination of socially awkward, short-fused and carefree, so I doubt she genuinely hated Kotarou at all. tl;dr: she’s not the type to hold grudges for long, and the anime shows this at least.
Of course the VN paced the dynamic of the two better ((VN-only content)like Kotarou randomly sharing English trivias with her before class), but this is still pretty reasonable.