I am the world's biggest Guns N' Roses fan. I dare you to find someone who is a bigger fanboy.
Basically, Axl just screwed over everyone else in the band. Even in their early days he was a total diva, coming on late and nearly causing riots because of it. Some band members left after the UYI albums, some were fired, all mainly due to Axl being a tyrant and demanding ownership of the GnR name, even forcing the other guys to sign a contract that gave him ownership of it all. He also started working on an album that had a lot of synthesizers in it, and the other guys weren't too keen on it... so eventually Axl was left by himself. I believe the final straw for Slash was when Axl secretly hired another guitarist to rerecord Slash's parts and use those without even telling Slash.
So he basically spent all those years trying to create the 'perfect' album because he's a huge perfectionist. I have to say... I'm a massive fan of all of their albums, except The Spaghetti Incident and Lies, since those really are more B-side releases/cover albums than anything. Those ones still have classic songs, though. Appetite is amazing, Use Your Illusions I & II are even better (except for the alternate version of Don't Cry and My World... awful)... great albums.
I honestly believe Chinese Democracy is an amazing album, too. There are some incredible tunes on there - Prostitute's ending has one of the most beautiful moments in rock I've ever heard! Street of Dreams is wonderful as well. Axl's vocals are a bit... too much at times, just because of how pitch corrected and insanely high they are, but the guy can sing even better than he used to, as a bunch of YouTube videos from their 3-4 hour concerts a couple years ago prove. Chinese Democracy is just way different... I don't think it's fair to compare it to albums that were released almost 20 years before it. The lyrics aren't as great, but they're still good in their own way.
I really do think GnR has one of the most solid and timeless repertoires in rock, but that's just me. Estranged... one of my all-time favorite songs! That's my favorite song to play and sing at the piano, especially with the piano solo.
Anyway, I could go on forever about how much I like GnR, but I'll stop here as I've already rambled too much!