My fifth grader and I enjoyed Kristine George's Emma Dilemma, but we definitely treated it as a picture book rather than a poetry book. In fact, P threatened to stop reading if I mentioned the p- word, but he has a vicious prose preference. It's true that few of the pages stood alone; the evocative words worked with the illustrations to paint the story of a loving older sister and her sometimes pesky sibling.
It did rub against one of my current sore spots -- false childhood guilt. I dislike reading books that encourage kids to assume guilt they shouldn't own -- guilt is a very healthy emotion that reflects a missed opportunity, not one that reflects bad luck or accidents. When Emma falls towards the end of the story, it was clear to me and P that big sister had nothing to reproach herself for, but of course she feels guilty anyway. Which I know kids do sometimes, but I've tripped across too much child guilt lately to enjoy it.
Here's my test -- if you look back and you wouldn't change what you did, then you aren't feeling guilt. (You could be feeling shame, but that implies that you wish you were the person who would change what you did but you aren't.) You may be wallowing in self-pity, but that's a different emotion, and I want my kids to learn the difference.
But besides my little hang-up, it was a bright, companionable book that we liked a lot. Our favorite page had the girls playing cards, the mom advocating cheating to let Emma win (P and I were shocked), and the clever but rejected solution of 52-pick up, which had P chortling. I got A and X to read it as well, since A is an actual big sister, and they also liked it (especially A). We ended up with a fun discussion about poetry -- all the kids were sure it was not a poetry book, but we agreed that a new word was needed for books that weren't poetry but had "picture book" language that felt a little richer than plain prose.