Darvas was probably one of the first modern momentum traders. He made his fortune many years ago in the fifties and came out with his famous and classic book "How I made two million dollars in the stock market". This simplistic and screaming title introduced what turned out for me to be a really honestly written book, describing a system that seemed to be the most straightforward thing there is. Perhaps it was Darvas' naivety that allowed him to find this simple and direct strategy and then to write such a friendly book. Candidly he walks the reader almost half of the book through his personal missteps in the stock market and later he never attributed what he found to his genius or his hard work, instead he just said humble things like "There was nothing else to do while Texas Instruments went to work for me".
The most complete package about Nicolas Darvas and his other books, including his main book itself, and more unpublished info about bis boxes system can be found here:
The next generation of Darvas' boxes system
This system shares some similarities with the one of Nicolas Darvas, but has a much more elaborated entry system, which matches better modern market behavior. The selection process for stocks that are followed is also more refined. Still, in some way it could be viewed as being simple. It uses the daily bar chart, does not need sophisticated technical analysis support and demands only basic fundamental data. In this spirit, this trading system could be considered the successor of Darvas' boxes system.
Compared on a more abstract level, the Darvas strategy demands a specific entry pattern that often doesn't come. Either you miss the boat or the box idea has to be "stretched" to get on board in many cases.