I have nothing against teachers assigning sestinas or pantoums. I think they are very useful exercises. And I’m a big fan of formal qualities in poetry; that is, when they’re done well. But more often than not, the sestina/pantoum reads like a form that had to be filled out—name, address, social security number.
Of course these are both very difficult forms, so it’s no surprise you might feel a great sense of accomplishment at having completed one. But income tax forms are also very difficult to fill out, and that doesn’t make them poetry.
So when you’re thinking about sending out your next sestina/pantoum, ask yourself, is the subject I’m writing about one that would be served by a lot of repetition? Does the repetition serve to move the poem forward, rather than merely to bring it back around to where it started?
You should know I’m probably more biased against these two forms than are most of the poetry editors and readers here. I just happen not to like them. But it seems only fair to be honest about my biases as a reader.