The gimmick is that all of its forty songs last for exactly 60 seconds (not counting the bonus tracks in the CD release, of course). Why did they do that? Well, what The Residents are saying is that pop music in general is just the same verse & chorus repetition over and over, with a middle section thrown in. Cut out the fat and it's only one minute long.
Coincidentally or not, most commercial jingles also last around one minute. The Residents therefore concluded that "jingles are the music of America". With that logically proved point, The Residents created their own Top 40, and it's one of their best releases ever.
Of course, the most relevant complaint you would have with this album is that there isn't enough time to appreciate the music. As Penn Jillette said in Ralph Records' 10th Anniversary Special, "it just starts getting good, you start tapping your foot, and it ends! And another time, you tap your foot, and it ends! And another time, you tap your foot, and it ends!"
I'd say that's a valid complaint. I didn't pay attention to half of the music the first time I listened to this, and when I brought my attention back to it, I had already gone through, like, ten songs! So, to fully listen to this album, you gotta concentrate to make sure you don't miss a single song.
Despite that inevitable problem, I did appreciate the album much more the second time I listened to it. And a lot of the songs are actually really catchy! "Easter Woman", "Red Rider", "Floyd", "Dimples and Toes", "Moisture", "When We Were Young", and many others.
The music itself is a bit more synthesized than their previous albums, and that's an important thing to note, because The Residents' music would get more and more synthesized as time passed by. This album still has lots of real instruments though (I think "Possessions" and "The Coming of the Crow" have real drumsets). It definitely doesn't sound cheap at all, although a bit minimalistic at times ("Secrets", "Japanese Watercolor", "Act of Being Polite").
Overall, The Commercial Album, despite its weirdness, is still an awesome listen, and an important mark in The Residents' history. I definitely recommend it.