My 6 and 8 year old DDs did it this year and we thought it was pretty well organized. Parents could/did run with their kids, but you didn't have to. My girls decided they wanted to run without us. I was a little concerned about that, but it worked out ok. The course runs around the fields out at WWoS, so you can really see them the whole time since its so wide open.
My only complaint was the finish line. As the kids started crossing the line, parents were crowding in to take pictures. The entire finish line area was jam packed and it was REALLY difficult to find my kids. I wish that Disney had asked parents to stay out of the finish line area or at least move elsewhere for hugs and photos once their kids crossed the line. The kids bibs came with a "Parent Claim" tag, but I have no idea why! It was a free-for-all at the end. I told my girls before the race to stay inside the fenced finish area until we met them, so I wasn't really worried about their safety, but it would have been easy for a kid to get lost or confused in all the shuffle.
Nonetheless, we thought it was a great event and we would do it again. The kids had a lot of fun and enjoyed wearing their t-shirts and medals to school on Monday.
They counted them down, and off they ran. I was able to catch them running in 3 different spots for pictures, and was able to get my little one back for a visit and pictures with Mickey while we waited. It is also the only timed kids' race - they use a D-tag. In the goodie bag, we got a certificate for Billy with a place to fill in his finish time. They also get a different medal for the Mickey Mile than the other races. My son is already planning for next year's race! 
