Poetry is the unique expression, commonly in verse form, of universal experience.
What do I mean by that?
Okay, first off, let’s talk universal experience. The goal of poetry is to achieve a level of resonance—preferably emotional, but possibly intellectual—with a segment of readership. This means that the love story of two sentient blobs existing in the substrata of Mars, for instance, is probably best explored through speculative fiction or extrapolative essay, since you’d be hard-pressed to find a readership that is likely to emotionally identify with the scenario. Such a subject can conceivably be used as metaphor, but it should be illustrative rather than topical—in effect, your point should be something like “The experience of love is the same throughout the cosmos”, rather than “Sentient blob love is tragic, yet beautiful”. No one really cares what sentient blob love is like, except in terms of how it relates to their own experience.
In other words, what you should be trying to do, with poetry, is to evoke a sense of recognition. If people say, “Wow, that’s so true!” after reading your work, then congratulations, you’ve succeeded. If, on the other hand, they say, “Wow, what a cool idea!”, then do not pass Go, do not collect two hundred dollars. Ideas for ideas’ sake and weirdness for weirdness’s sake are less poetry than they are masturbation in verse form.
Which leads neatly to my next major point (verse form, not masturbation), except that I’ll be talking about it in a succeeding entry, as this one has gotten too long already.
As with all my little online ruminations, take all this with a sack of salt: I’m not really an authority, and I could be wrong. If, however, you ask me—as people seem to do—to critique your work, then expect me to apply the above criteria as I’ve explained it. And go on writing poetry… but don’t call yourself a poet unless someone you respect does it first.