(NASDAQ:AMZN) is one of the most controversial stocks in our marketplace. It looks tremendously overvalued when you look at standard metrics, yet it always seems to prove naysayers wrong time and again. In 2012, it worked up a reputation for not only being hugely successful, but also for being the kind of aggressor that can put other companies -- once thought stable -- out of business.

Last year, blaming Amazon for Best Buy's (NYSE:BBY) difficulties became a common theme. Hardly anyone could discuss Best Buy's struggles without mentioning a phenomenon known as "showrooming," in which consumers simply use a brick-and-mortar store to look at merchandise they intend to buy online later. In fact, a recent Harris poll of shoppers who had indulged in that behavior indicated that an entire quarter of them had used Best Buy for their window-shopping needs.

And the likelihood that many consumers will buy online at is pretty high due to its incredibly strong, trusted, and well-known brand. In the last 12 months, Amazon generated $57.26 billion in revenue. Amazon competes with just about any retailer you can think of, but compare that sales figure with online discounter (NASDAQ:OSTK), which reported about $1.1 billion in sales in the same 12-month period.

Of course, that's not the greatest comparison. In fact, Amazon competes in far more markets than any retailer, online or off, and therefore it's difficult to even find an apples-to-apples comparison. The ways in which Amazon is an extremely diversified and innovative company -- and pretty terrifying to many different kinds of rivals -- is almost too complex to fully comprehend.

In just one example, Netflix's (NASDAQ:NFLX) recent Christmas Eve outage was actually Amazon's fault. Granted, that wasn't a proud moment for Amazon -- and continued snafus like that one could hurt its business -- but it is a reminder that one Amazon's many businesses is providing Web services to quite a few companies behind the scenes, such as Pinterest and Foursquare.

That, of course, doesn't even sum up the complexity between Amazon and Netflix though. Amazon's doing a great job competing with Netflix's Instant service with its own service allowing customers to rent or buy movies to stream at home. In fact, Amazon's streaming content has often seemed better than Netflix's offerings this past year.

Barnes & Noble's (NYSE:BKS) Nook sales lost momentum during the holidays, making it look likely that other companies' tablet products, particularly Amazon's Kindle offerings, are squeezing Nook into the corner. This is a major setback for the continuing survival of Barnes & Noble, since the Nook was one of the few bright spots the retailer had going for it. We already know what became of bookseller Borders, and while Borders' problems were severe, the shift to e-books was no small factor of its demise.

I bought shares of Amazon for the Prosocial Portfolio I'm managing for almost exactly one year ago. I purchased the shares on weakness, around $184 per share, despite the fact that at the time they were trading at a whopping 89 times forward earnings, and I haven't regretted the decision since. Right now, it's trading at 149 times forward earnings.

Am I selling? No. I actually think Amazon can keep up amazing growth, and likely outpace the growth that analysts and investors can now speculate about over the long haul. And be patient, potential investors: every once in a blue moon, Amazon gets a cyclical sucker punch to its share price. This occurs when analysts and then investors freak out about Amazon's low margins and the stock gets a takedown, so waiting for a period of weakness to buy in or add to positions is a good strategy.

Over the very long haul, though, I do believe Amazon's going to keep up the stunning growth and provide products and services that we probably can't even imagine now. Founder and CEO Jeff Bezos is a visionary leader who is also one of Amazon's particular competitive advantages. Stand back and watch Amazon do what it does best: amaze us all.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.