Seems like an ok site from what I've seen. There are some issues with its interpretations (some documented, others not) but for the most part things seem fairly accurate in explaining basic macro syntax pieces.
Biggest problem though is for the novice, they still likely have to dig around or ask for help to make their macro. The tool doesn't help you make a new macro, but rather it just interprets one you already have. It's just another tool to help with the process of learning and provides a slightly different viewpoint than the written guides and articles.
"In anything, if you want to go from just a beginner to a pro, you need a montage." /w TankSpot WTB Montage for Raiders.