I celebrated the 500-mile mark by writing a review of my new bike, and posted it on the Epinions.com website - HERE.
I like Epinions, because it's real reviews by real consumers. I've gotten valuable information there. (Of course, reviews by "real consumers" are a mixed bag. I'd say a large percentage of the reviews posted at Amazon.com range between grammatically flawed and unreadable. But... I better be careful! After all, I may be inviting readers to read my review with a particularly critical eye!)
Is 500 miles enough experience to write an in-depth review? Probably not. But it's probably enough to give me a very accurate first impression of the product... and I can always go back and add some notes a year or two later if it turns out the new bike is a real lemon!