Just opinion, of course, but Reign in Blood fucking kicks ass. To me, each song does flow into the next, and the album can easily be enjoyed from start to finish in one listen, which, I like to think was intentional.
Damn, you got me. I guess I should sell my King Diamond, Morbid Angel, Death, Uriah Heep, Black Sabbath, Iron Maiden and Judas Priest records then. (Sorry but a bullshit assumption deserves a condescending retort :P) It has more to do with personal taste.
Reign in Blood had some cool riffs but lacks the variety, the dynamic unpredictable songwriting the first two have. It also doesn't have the bestial/hellish/unholy feeling, or the attitude that I loved about the first two. It lost all these in favor of trying to be the fastest thrash album of the 80's, and this emphasis on speed starts to feel very forced after a while. Outside of "Rain in Blood" (which is undeniably a classic, if only this song was featured on "Hell Awaits"), the songs in Reign in Blood are distinct and have the "Slayer" sound but they don't stand out from eachother IMO. I don't really care how short an album is, I own some records that are under ten minutes in length. Another 10 or 15 minutes of fast tracks without tempo changes would have made it a chore to listen to.
That said, I don't hate RiB or anything, I'm just indifferent to it and don't listen to it, I prefer to love and appreciate Slayer for the good stuff they've done.... there are much worse bands to get offended at. Either way I think lets unite on the Slayer that we do like instead of arguing over personal taste. :P
NP - "Hell Awaits"... Jeff really wrote some masterpiece tracks for this album. Rest in peace brother.