Darrell Bock, a professor of New Testament at Dallas Theological Seminary, says Knohl may be reaching too far with his translation. "The problem here is that there's not enough text to be able to be really confident about what the passage itself is reading in order to build a theory around it," he says.That sounds about right to me, and I've made similar comments here and here.
Ben Witherington III, professor of New Testament interpretation at Asbury Theological Seminary, agrees that Knohl offers a lot of conjecture to fill the gaps and holes in the text. "But what if he's right?" Witherington asks. "It just means that there were more persons in early Judaism, other than Jesus and his followers, who were talking about a dying and rising messiah. That's not a problem for Christianity, as far as I can see."
Bock doesn't see much of interest for scholars. "The text deals with some type of angelic communication, but beyond that it's very hard to tell what all is going on," he says. "The connection to messiah is virtually absent."
But Witherington calls it an interesting document, beyond the rarity of an ink inscription on stone. He thinks scholars will continue to be drawn to it.
"It's some kind of prophetic, apocalyptic Jewish text," he says. "I think this stone is as significant as many of the Dead Sea Scrolls. But it doesn't seem to have any value for the discussion of Jesus except by way of general background text, like the Dead Sea Scrolls."
Further background here, here, here, and here.