I think samandereas summed it up perfectly.

Oasis were always sold to Brits as the next Beatles and always sold to Americans as an alternative to grunge. But really they were just a derivative, mediocre band devoid of creativity with a whiny front man who acted like he was God's gift despite not even being able to sing his way out of a wet paper sack, consistently awful and embarrassingly empty lyrics and song compositions so basic as to place them beneath your average high school garage band.

Oasis is not any better than one of those third tier U.S. grunge bands that popped up in the 90s hoping to ride the Nirvana wave. They are also no better than the majority of 80s hair metal acts people like to make fun of these days. The fact they are ranked above clearly far superior bands like Queen, Pearl Jam, The Cure, Black Sabbath and scores of others on here is simply laughable.

FIRst album is AMAZING. Rock n roll to live and die by. 2nd is full of good songs. 3rd is a bit ok. After that they became kinda bland but ive gotta five em 90/100 for their massive list of great songs and cool attitude

Without doubt the most overrated, overhyped band of all time. So derivative. Beatles wannabes.

biblical

haven't heard many songs from this band, but the ones I have listened to, I couldn't get through the entire track without turning it off. Very annoying vocals

Much prefer Joy Division and James.
Some points however for lifting the nineties for a brief time.

Good artist, good brit pop.

Oasis is one of those bands that people love to hate. They came onto the scene when the grunge movement was coming to halt. Oasis started off their career with an amazing debut, one of the best all time. They followed it up with another album considered even better than their debut. They produced some pretty great songs lyrically and musically on those two albums, and the albums as a whole felt complete. After those first two albums, they still made some decent songs, but none of their albums truly compared to the first two. Tension between the Gallagher brothers caused their downfall. They had a lot of potential, but ultimately could not deliver the same consistent level of quality.

Would I say they were the best band of the Manchester-Britpop era? Absolutely.

Would I say they were a Top 10 nineties band? Probably.

Would I say they were the best band since The Beatles? Definitely not, not even close.

It's a shame they couldn't put together any truly amazing albums after their first two.

I think they get all this hate for two reasons:
1. Their personality. Specially Liam's constant disrespect towards other bands throw people off.
2. Their fans. Oasis are one of those rock bands that are "untouchable". If you criticize them you'll instantly have tons of outraged Oasis fans insulting you.

Musically they're pretty good, though they seem a bit "formulaic", always use the same progressions and guitar tone with too little experimentation for my taste.