Realistic Eroded Rivers is a utility that shows how to create an excellent river. Moogle has done a very good job, but the utility lacks in just one area.
The instructions are given via an HTML document, meaning that it just can't give the clarity an example scenario would have given. The pictures are a little bit small, and you have a hard time seeing what has been done. However, the final product looks great, and you can tell that some work was put into it.
I have to give Moogle a 4.5, because although it was a great piece of work, the pictures aren't too clear and really should have been put in a scenario. If this one thing had been overcome, I would not have hesitated to give it a 5.0. If you are having trouble creating the perfect river, I would recommend this utility.