In a poem that argues against the value of mere appearances, you shouldn't expect a whole lot of attention to rigid form and meter. Still, we do get some symmetry in terms of form that is worth noting. Yes, in the "Line-By-Line Summary" we did discuss those rhyming couplets that each stanza ends with. Also, there's that famous refrain, in the very last line of each stanza. As well, both stanzas have eight lines, so it's not like Stevens is totally abandoning the idea of structure here.
But perhaps that's the point. In a poem that's designed to get us to re-examine our reliance on appearances, this poem—at a glance—gives some the appearances of stylized form. Really, though, when you start to trace the meter, or rhythm of the language, you realize that there is much more playfulness at work than a strict poetic form would allow. It's as though the poem is acknowledging the importance of form overall, but really trying to work against that idea once you start paying closer attention to the language.
Along those same lines, consider how much enjambment is going on here. One idea (line) flows into the next, creating something that looks sort of like a casual, free-form conversation. Nothing is forced to fit into a specific box or form, aside from the couplets. It's almost as if the poem's language itself is allowed to just be.
Finally, let's return to those couplets for just a moment. They're the most direct, most important, and yet most stylized lines in this anti-style poem. So, what's up with that? Couldn't Stevens have delivered this idea another way? Well, one theory is that these rhyming lines are indicative of a touch of irony. And that might be part of the point, too. This poem celebrates… celebration, enjoyment, fun. By couching its message most succinctly in this very formal way, it's as if Stevens is also poking fun of the staid, formal poetic tradition himself. It's like a guy in a tuxedo, wearing a party hat and sticking out his tongue. Even in its most formal moments, the poem is telling us to relax, unwind, and embrace the reality of the moment.