Top critical review
Reviewed in the United States on October 27, 2020
Other reviews hit the nail on the head--this collection is a real hodge podge that doesn't necessarily enhance your understanding of the Dark Nights Metal event and is highly skippable. The first two issues are like a "prologue" to Metal, yes, and they do have some tidbits, but nothing you absolutely need to jump into the event.
On the flipside, the rest of the book is a smattering of Final Crisis, (The Return of Bruce Wayne?), Endgame, and Nightwing that will leave you scratching your head. If you're a person who needs extra background, this will confuse the hell out of you even more. And if you're like me, and you actually read all of those previously, you'll go "okay, I guess that was a refresher of sorts," but it's too jarring to really enhance your understanding or enjoyment of Metal.
TL;DR-The first two issues have new info, but don't justify the purchase. The rest of the book is a messy, hard to follow collection of previous stories.