For me, part of the problem is that there seem to be three different versions of the Beatles. There's the pop-Beatles, and then there's the Rubber Soul onward Beatles when the Beatles were moving towards psychadelic rock, and then there's the post-India Beatles that couldn't seem to decide if they were going to be experimental or move back to mainstream music (e.g. the White Album).
Towards the end of the Beatles, there's an awful lot of what I consider noise on the Beatles albums, Revolution 9 being the most obvious example of that kind of music. I don't know it it was just the 1960s, if the members of the band wanted to try something new, Yoko Ono, the drugs, sheer exhaustion, or what it was, but the albums are very uneven by the end of the decade. McCartney writes Blackbird and follows it up with Ob-La-Di, Ob-la-Da for example. It's almost like the Beatles couldn't find their sound, or maybe more accuratly wanted to change their sound and didn't know which way to go.
I won't deny that the Beatles were huge in the music scene in the 1960s, but compared to other period groups, I don't think the Beatles albums, especially the later albums, have aged well. Overall, I think the Beatles were an important band, but I don't think they were the greatest band musically (although I do think individually McCartney and Harrison rank right up there) and I do not think they are as great as many people think they are.