He refuses to dismiss Many-Worlds theory because it seems like nonsense. Okay, fair enough.
He does point out that probabilities make no sense in the theory. You might think that a probable event is one that occurs in most of the worlds, but the proponents of Many-Worlds adamantly deny that.
I don't think most people appreciate what a devastating critique this is. A lot of smart people take Many-Worlds seriously, so you would think that they have some explanation for probabilities, but they really don't. They have no way to make sense out of the idea that some events are more probable than others. They just give up on the concept.
Giving up on probability means giving up on the whole scientific enterprise. What is science, if not to predict some events as being more probable than others?
Just to repeat, Many-Worlds theory is worthless because it is unable to ever say that one event is any more probable than any other.
Maudlin also explains that decoherence does not solve the measurement problem that bugged Schroedinger and others. Wasn't that the main point of Many-Worlds theory? If the theory does not do that, then what is the point?
Supposedly the Copenhagen Interpretation of quantum mechanics is deficient because it does not explain how the wave function collapses when a measurement is made. The Many-Worlds theory says that the wave function never really collapses, but appears to collapse because of interaction with the observer's wave function and decoherence. The other possible outcomes show up as parallel universes. The Many-Worlds advocates say we need to accept the parallel universes in order to correct this Copenhagen deficiency. But they don't solve the measurement problem anyway.
So Maudlin destroys Many-Worlds in about 5 minutes. But being a good philosopher, he does not reject it. Believe it if you want. Philosophers say it is just fine to believe in theories that have no theoretical advantages or practical utility.