I had been hoping that this sequel would give Pierce Brosnan a chance to sing again. I was not disappointed, he does a nice rendition of part of "SOS"...a decade ago I was the only one I knew to defend Pierce's singing in the first movie, but his version of the same song is much better ten years later.
It is rare that a sequel lives up to an original movie, and even rarer that a sequel is actually better. This is superior in just about every way. Yes, I guess now that the term "prequel" is in common use, this movie is both a "sequel" and a "prequel" at the same time.
The director seems to have taken a leaf out of the philosophy of the principal character, Donna, and "thrown caution to the wind" allowing the whole thing to romp with exuberance that borders on becoming silly or a parody, but he keeps a firm hand guiding it so it never crosses that line. Instead it stays frothy, bubbly and fun. The "over the top" approach can be richly entertaining if it is defty held in control. Think of Johnny Depp in "Pirates of the Caribbean" or John Wayne in "True Grit" ...this works here.
Not only is the direction vastly superior to the first movie, so is the editing. This shows up splendidly in song sequences, with "One of Us" as a duet early in the film being a stunning standout. I thought the director of the first movie showed an almost complete lack of understanding about how to direct s movie. Perhaps she got the stage production to work but I thought her direction of the movie was inept.
It is better scripted than the original, with the songs integrated better with the plot. It seemed far less forced. OK, the "Waterloo" scene is a definite stretch, but once again the over the top approach to the number is enjoyable and entertaining. Having Richard Curtis onboard must have helped quite a bit, he is a master with comedic material that still has bite.
I knew that Meryl Streep was billed in the cast as well as Cher, and Cher appeared in the trailer, but as the movie neared its end neither had appeared. It was worth the wait. Cher does an excellent cover of "Fernando" with Andy Garcia, and Meryl a poignant duet with Amanda Seyfried, mother and daughter reaching the end of plot arcs that have paralled each other. Meryl's performance in the first movie was the only one she ever rendered with which I was disappointed, but she nails it here. I think the director of the first movie is at least partly responsible for the results on screen that didn't impress me.
There is a beautifully large production number of "Super Trouper" under the credits at the end and there is a funny post-credits scene that virtually everyone in the audience saw, which is unusual. It takes skill to hold an audience to that point, especially these days.
This is what a musical is supposed to be like, something to lift the spirits.
About the only negative for me was not giving Christine Baranski a solo. I thought her scene with one in the first film was the best in that movie. I also would have let Pierce finish his song, he was doing just fine with it.
I have not yet read a word about this in reviews. I guess I will now do so. I know people that tend to adore the first movie, and it will be interesting to hear what they think about it in a comparison. I can't be this wrong. There must be critics that also think this is an massive improvement on the first movie.
But to answer your question why they made a sequel, I would guess the answer is "money" as the first movie was a hit. This sequel opened very strong at the box office.