Sarah Cooper is very, very good at conveying a great deal of tumult with her facial expressions. What always sold her Trump lip-sync videos was her range of emotions which managed to comment on the insanity of her given material without changing a word or a beat. Indeed, the lip-synching segments of the special are the strongest bits- not because she is repeating herself but because Cooper is allowing herself to be as hilarious as she really is. The weakest bits are where Cooper is playing straight man to her funny guests.
The special is both helped and hurt by the parade of celebrity cameos. Helped because the celebrities (especially Maya Rudolph and Aubrey Plaza) are such a delight. Rudolph is particularly scene stealing. But on the whole they serve to detract from Cooper's comedic voice- never by outshining it, exactly, more by distracting from it. The tonal shifts should work better than they do- the almost stream of consciousness flow is Pythonesque in a way, but that just means this might have worked better as a 1/2 hour pilot for a new ensemble sketch show rather than an hour showcase for ostensibly one person.
All in all it is worth a watch, but I think we can expect better special from Sarah Cooper in the future and I do hope we get one!