Questions
1) What does a good poem need?
2) Are metre and rhythm important?
Answers
1) A good poem needs rhyme but a really good poem (even a great poem) also needs metre and rhythm.
Make sure your rhyme is not contrived. Don't use false rhymes (rhyming words with themselves). If you're writing free verse, then you don't need rhyme of course, but metre and rhythm still need to be there.
2) Indeed. See question 1.