I was initially surprised that there was this much discussion, but, at the risk of sounding like a "good ol' days!" guy, I think you had to live in the GNR prime to get the full feel. As a result, people who were teens during Ten/Nevermind might have the same affinity for those records in the same way. Fair enough.
In the late 80's, GNR was EVERYWHERE. They opened shows for Aerosmith and the Rolling Stones and there wouldn't be an empty seat in the house. Every week was another story about them and their debauchary but unlike other bands, they had the goods to back it up. AfD was dismissed by some critics as being a "one trick pony"...just in time for Lies ("Patience") to come out and shock everyone. The band started the UYI tours in May before the Sept release of the records and sold out every venue they played despite not having fresh material for years. The band was a phenomenal stage-act during the AfD tours despite being completely drunk/high.
I realize we are talking about the record itself, but part of the allure of AfD was that no matter how insane the band behaved and how ridiculous their antics, they had an unbelievable, lightning in a bottle, raw rock record that could not be denied by even the harshest critic. I can only imagine someone buying it for Sweet Child and Jungle, popping the tape in and getting trampled by a heard of elephants for the next 60 minutes. There is not a single letup on the whole thing, sort of like the first Ramones record. Even in it's weaker moments like Think About You and Out To Get Me (which are still awesome) it never lets up. I saw a Ramones documentary on Saturday where a producer said, "As soon as you played their debut for the first time, half of your record collection became obsolete." That's what AfD did for hair-metal, hard rock which despite our mockery now was a HUGE force in music. Imagine right now if a brand new rap artist releasing a record that was both accessible to the general audience yet so brialliant and full of talent that other artist's careers were literally over. That was the AfD affect.
HEre were these heroin using, glammed out, homeless guys not so different from the rest of the LA scene on the outside who simply rocked like no one else.
It's one of the only rock records of the era (harkening back to the Stones' best work) where the guitarists are doing unique things at the same time and the bass isn't just mimicing the bass note of the rhythm guitar. Musically, it's phenomenal and in uncharted waters despite the fact that it was recorded by severely intoxicated people with no musical training at all. Some oft he riffs are so inspired by Aerosmith that it could be called a rip-off if not for the fact that GNR absolutely OWNED those riffs and made them their own. Lyrically, it's about girls, drugs, paranoia, and the streets...the exact same material that Crue, Bon Jovi, Poison were offering yet it stood out as inarguably honest and violent.
As for marketing, it sold 15 million copies in 3 years despite the fact it didn't have a single ballad nor did it have a 4th single/video. Contemporary albums ALWAYS had a ballad come out 3rd yet GNR's 3rd single was a rock song featuring a 2 minute double-time guitar solo at the end.
I understand other people who think that certain albums are as good or what not, but you have to realize the record is 25+ years old and if it were released tomorrow, it would still sound revolutionary.
Pearl Jam's Ten, Radiohead, RHCP, Metallica...all great records and artists. And they've influenced hundreds of bands along the way. But AfD is so unique that NOTHING sounds anything like it more than 2 decades later. It's as if it was so unique and powerful that artists are stumped as to how to draw from it.
THere will never be another GNR, never be another AfD, and never be another time when a single Hydrogen-Bomb of a band so thoroughly ruled the rock scene.