Here's most of Dave Barry's piece about the greatness of Gloria:
I think one of the greatest works of music ever written—and I include Beethoven's Ninth Symphony in this category—is Van Morrison's Gloria. The brilliance of this song is evident from the opening lyrics:
"Like to tell you 'bout my baby, you know she comes around;
Just about 5 feet 4, from her head to the ground."
Right away, you know exactly what this song is about. Also, she comes around. She is not playing hard to get. We later learn that she comes around "just about midnight," and "she knock upon my door." In other words, she is the perfect woman if you're a teenage male, which is what Van Morrison was in 1963 when he wrote Gloria.
It's not just the lyrics that make Gloria a masterpiece. It has a superb musical structure, by which I mean: only three chords. This is where the Beatles went wrong. Don't misunderstand me: The Beatles were a very good musical group. But, as I discovered when I was in high school learning electric guitar in an effort to become a rock legend, the Beatles put way too many chords in their songs, including mutant chords such as "F sharp minor." In my opinion, this is why they broke up. A band can play only so many chords.
Whereas Gloria has just the three chords, and they are basic, simple, hardworking blue-collar chords, namely, E, D and A. They are always played in that order. This makes it an easy song to learn. If you ask a group of mediocre garage-band musicians to play, for example, Help! they will sound like building demolition. Whereas if you ask them to play Gloria, they will, given a few minutes of practice, sound pretty darned close to Them.
This is why for half a century Gloria has been part of the repertoire of thousands of bands sharing a passion for gritty rock 'n' roll music that does not require a ton of musicianship. I have been in several of those bands. In the late '60s, at Haverford College, I belonged to a band called the Federal Duck (don't ask). We played dances, mixers and frat parties at colleges all over the greater Philadelphia area, and we always played Gloria, sometimes more than once, because (a) we might have, on occasion, been a tad impaired, and (b) the song always got a strong reaction from the crowd. As soon as the frat brothers heard the opening chords—E, D and of course A—they would lurch out onto the dance floor with their dates and commence gyrating. Sometimes they would also throw up on their dates, but that only added to the grit quotient.