I've read the draft screenplay, and it was very interesting. But however the revision process happened specifically, the finished version is obviously much better. Aside from Vader being Luke's father, and the hyperdrive being busted for the whole film, pretty much everything in the structure of the story is recognisably there, albeit unpolished and with a lot of unnecessary exposition.

It's quite clear that any claims of the 'saga' being all planned out in advance are obviously ludicrous in the face of having read this, though.