I saw the show last night and not sure if changes had been made yet (I doubt it given the schedule) but I LOVED it and thought everything ran pretty smoothly. The 1st Act may have been a bit long but it didn't feel that bulky. Erika as Cady is wonderful and she's clearly the lead, which baffles me as to why she isn't on the promotional material. She has a beautiful voice and some really soaring moments. Plays both vulnerable and then confident in the 2nd Act well. I really liked "Wild Life," "Apex Predator" and "Crazy in Love"
Regina didn't feel like the lead at all -- definitely more of a supporting role, and I agree with others that say she isn't as fully fleshed out as she could be. Taylor was fine I thought, but at points it was hard to hear some of her lines, but having seen shows at The National before, the acoustics aren't the best and I was in the balcony. Kate as Karen was HILARIOUS. Her number is so funny and I'm really hoping they don't cut it. It got lots of laughs. Damien/Janis as the narrators worked really well, and I loved both Gray and Barrett.
Also, the actors do move the props themselves but it really works. They transition pretty seamlessly through classroom scenes and it had a good pace. I thought the choreography was great, particularly the fight scene and the cafeteria. The screens behind it work well too, and the bus scene and the way they do it is hilarious.
Overall, I really liked it. Was it Hamilton or DEH? No, but it's funny and witty and Fey's book has some nice updates. The audience was really into it and laughing at a lot of the lines, especially the main ones from the movie of course (She doesn't even go here!)
Oh, and Kerry as the Ms. Norbury/Mrs. George was great. You wouldn't even know you're seeing the same actress, and she had to make some really fast wig/costume change turnarounds work, so I was impressed by that. The song she has as Regina's mom is ok -- it just seemed to come out of nowhere and was probably the weakest. I appreciate they're trying to flesh her out more, but I would have preferred to see more of her as Ms. Norbury -- where they have her look like a dead ringer for Tina Fey.
Overall, 8.5/10. I'm going to try to go again while they're here in DC and get closer seats.