Unfortunately, for metal fans, much of this is an embarrassing selection of songs that do not truly represent the genre. What were the compilers thinking?
Let’s start with the obvious. How can any box set that represents heavy metal exclude AC/DC? They didn't have to include "Back in Black" -- they could have selected “Jailbreak” or any other Bon Scott-era material. They also didn't include Ozzy Osbourne or any early Black Sabbath, and one could argue Sabbath is the band that STARTED metal.
Finally, if you're going to include a heavy metal classic, don't edit it. The edited version of Iron Butterfly's “In-A-Gadda-Da-Vida” excludes the thunderous drum solo that made this classic song heavy metal. At the time, metal was a reaction against the norm -- as it is today -- and yet, the trait that made this song unique is on the cutting room floor.
Oh, it gets worse. Why did they choose Deep Purple's "Highway Star" instead of "Smoke On The Water"? Why did they choose Alice Cooper's "Billion Dollar Babies" instead of "Teenage Frankenstein" or even "School's Out" -- the latter capturing the rebellion that is often associated as a motive for bands in this genre to write their material? 
The worst offense is choosing Rush's "
Disc two is better. I grew up on the bands on the second half of this release. Motorhead's "Ace of Spades," Diamond Head's "Am I Evil?," Judas Priest's "You've Got Another Thing Coming" and Iron Maiden's "The Number Of The Beast" were selected as the best songs of this epoch and I have no problem with them. But why isn't AC/DC on this disc? Queensryche's "Queen Of The Reich" captures the magic of that band -- vocalist Geoff Tate is one of the best in the genre. The first real heavy metal band to whom I ever listened, Grim Reaper, is missing. Their anthem "See You In Hell" could have easily replaced Raven's "Star War," as neither song did much commercially.
Disc three is nearly perfect, with a couple of exceptions. Why include Hanoi Rocks' "The Boulevard of Broken Dreams" instead of Tesla's "Modern Day Cowboy" or Def Leppard's "Saturday Night?" Other than that, this disc captures the early 80s metal scene perfectly. Quiet Riot's "Metal Health" and Dokken's "Into The Fire" are excellent choices. The inclusion of Accept's "Balls To The Wall" is perfect as is "Big Bottom" from Spinal Tap. Finally, thrash metal begins to make an appearance with tracks from Overkill ("Wrecking Crew"), Anthrax ("Caught In A Mosh") and Megadeth ("Peace Sells").
The final disc takes this release through 1991 and there are some good songs to finish this collection. Whitesnake's "Still Of The Night" starts out, followed by Great White, Poison and legendary DV founder Chris Thelen's favorite band, Faster Pussycat. Lita Ford's "Kiss Me Deadly" is more pop than metal.
The last 10 tracks score as the best assembly of the bands in this genre. Living Color's "Cult of Personality" starts things, which leads into Skid Row's "Youth Gone Wild" with Sebastian Bach's perfect vocals, followed by tracks from Testament, Slayer, Metallica, Pantera, Prong and Sepultura.
This collection picks up steam at the end but doesn't satisfy someone like me who grew up listening to the genre. The omissions are glaring and significant, kind of like excluding Beethoven in a classical box set. I really don't know if it was a copyright issue or the folks at Rhino couldn't get permission from the artists to be included or if it was a pure oversight by the people who assembled this set.
I only know that I wish they’d asked me to review their set list before embarrassing themselves…