Brief description by Israel Knohl:
"The first part describes an eschatological war: the nations of the world besiege Jerusalem, and the residents are expelled from the city in groups. This description is followed by a passage in which God sends “my servant David” to ask “Ephraim” – the Messiah Son of Joseph – to deliver a “sign.” From the context, it appears that this sign heralds the coming redemption.
The second part of the Gabriel Revelation focuses on death and resurrection – and the blood of the slain. The last paragraph cites the words of the Archangel Gabriel who commands a person to return to life after three days: “By three days, live.” "
On a scholarly assessment:
Matthias Henze, ed., HazonGabriel: New Readings of the Gabriel Revelation (Early Judaism and Its Literature 29; Atlanta, GA: Society of Biblical Literature, 2011).