This just means that you have to decide whether or not you like the poem, then you have to support your feelings with solid literary reasons. Here are some things to consider:
Do you identify with the poem at all? In other words, do you feel like it has anything to do with you, the contemporary reader, and your world? Why/Why not?
Is the poem understandable to you? Why/why not?
Do you like the vocabulary in the poem? Is the poet's word choice effective?
How about the structure? Does the poem have a rhyme scheme or rhythm? Is it divided into stanzas? Does the build/make up of the poem strike you as appropriate/effective?
How about the literary devices you learn in school? Does the poet make good use of simile, metaphor, symbolism, etc?