I saw it today and liked it a lot! I felt like it had a good balance of talking scenes and musical numbers, and the choreography was great ("Someone Gets Hurt" had especially cool choreography with everyone freezing and shaking, "Sexy" was a ton of fun with all the costumes and the sex cancer joke, and "Revenge Party" was so bright and cheerful for a song that includes lyrics about stuffing someone's remains into a bag and throwing them in the river). A few of the numbers were a little boring, mostly Cady's, but it's not that Angourie Rice was bad -- she wasn't -- it's just that Cady's numbers aren't as big and fun as pretty much everyone else's, and Angourie doesn't have as powerful of a voice as Reneé Rapp/Auliʻi Cravalho/Jaquel Spivey.
I loved how Reneé played Regina -- she was flirtier, edgier, more openly mean than Rachel McAdams' Regina. She really stole every scene she was in, and her voice was amazing in her musical numbers. "World Burn" is my favorite of hers, but they were all great.
I liked that they made Janis a lesbian; I always felt like she should have been. It's more of a betrayal for Regina to actually out someone and mock/ostracize them for being gay than it is to start a rumor that a straight person is gay. The change made Regina and Janis's backstory a lot richer. This Damian was excellent, too -- loved the little bit at the assembly with the fan, and his delivery of the iconic lines in the candy cane scene. (I also liked that the audience got to be Glen Coco.)
I thought they left in just enough from the original that this felt like a new take instead of a copy. I didn't feel like I was being nostalgia-baited (there were a few throwaway lines referencing the original, but the one big cameo was the closest they got to winking at and nudging us). The musical numbers set it apart even further. Nothing's ever going to surpass the original, but I'm definitely not mad they made this.