I've read that this sutra is one of the most direct routes to enlightenment and one of the most important, yet because future generations cannot handle this sutra, its disappearance was foretold.
I can find only a few English versions of this on the web and they each vary considerably, as if to indicate the prophecy is coming true. Among Buddhist teachers of certain (esoteric?) sects this is a favorite, but most teachers largely ignore it.
Can someone shed light on its relevance to the modern aspirant? What are its criticisms?
Why is it not more popular if its dire warnings are true? Are there reliable or canonical versions to follow? What is the history of this sutra?
Within Buddhism, there are very many important sutras. However, the most important sutra is the Shurangama Sutra. If there are places which have the Shurangama Sutra, then the Proper Dharma dwells in the world. If there is no Shurangama Sutra, then the Dharma-ending Age appears. Therefore, we Buddhist disciples, each and every one, must use our strength and our blood, sweat, and toil to protect the Shurangama Sutra. In the Sutra of the Ultimate Extinction of the Dharma, it says very, very clearly that in the Dharma-ending Age, the Shurangama Sutra will be the first to disappear. The rest of the sutras will follow. As long as Shurangama Sutra does not disappear, then the Proper Dharma Age is present.