This must have been a thrilling show to be at. It being a live album is helpful, giving everything an added oomph as well as some leeway in trying to mesh two oppositional sounds that a clinical studio environment would struggle with.
Given it's over TWO HOURS long and so peculiar it could make or break a fan but I actually fell somewhere in the middle. Being someone who’s recently gotten into Metallica via Master of Puppets and The Black Album, I found myself “interested” in the added context it gave me about the group rather than being lost in the music like I had been with those studio LPs. The material is generally strong but some of the efforts written post-The Black Album are more alternative rock rather than metal and sound less unique as a result. I also don’t need to hear James Hetfield’s vocals doused in auto-tune, I don’t think it suits the sound.
My main critique is that the orchestra should have been used more sparingly. All involved have pushed for the spectacular symphony to be all over S&M but given the material was not written with these instruments in mind the continual flourishes sometimes sound muddled and messy. When Metallica and the orchestra are on the same page, the classical musicians bolstering the band, it's a pretty effective whole (see: The Thing That Should Not Be and For Whom The Bell Tolls). But overall the concept is cooler than the final product.
Despite all this I admire Metallica for choosing to make a high effort “best of” record rather than just pushing out the hits in a more familiar form.