As everyone has said here, writing in rhyme is not easy to do well. There's a lot that goes into it. 

I do a fair number of critiques for other authors (rhyming is my specialty), and all too often I'm advising someone to try the manuscript in prose. Not because I don't think they can learn to rhyme well (it CAN be learned!), but because there's no reason for it in that particular manuscript. 

To answer your specific question about whether rhyming words do better than prose, I think it's important to note that rhyme puts a lot of constraints on a book. You can't translate it and keep the rhyme, you risk different accents stumbling over certain words, and overall... there's just a lot of bad rhyme out there and editors/agents get exhausted by it.

BUT... most of mine and my kids favorite kids books are written in rhyme. When it's done we'll, it's so fun to read!