The word "masterpiece" has been used in this thread, and I have to agree this album is a bonafide masterpiece. The songwriting and musicianship for Rush reached its pinnacle for this album. Whether or not you actually like a different Rush album more, or any other group more, I think the greatness of this album is undeniable. The only song I don't like listening to as much is Witch Hunt, but even that has a very creepy feel, something like Mussorgsky's Night on Bald Mountain or Berlioz's Symphonie Fantastique (Dream of a Witches Sabbath) and I can at least appreciate it if not love listening to it very often. Everything else on here is gold. I especially love The Camera Eye among Rush's lesser known songs.
It's not metal (although some of it is pretty hard), it's not pop (although 3 songs got a ton of mass appeal on Top 40 radio), it's obviously not Reggae (although a couple Rush songs have a Reggae rhythm), it's not electronic (although it has the perfect amount of synthesizers IMO of any Rush album.) It's just Rush, at their finest! Their version of Dark Side of the Moon, an absolute classic.