I really love that one! You call it disjointed, but hey, it's a fantasy! I read somewhere, when Beethoven performed it first time he had not even thought about a beginning (it was the day his 5 & 6 symphony, his fourth pc, parts of the C-Major Mass and the aria "Ah perfido!" would be performed, he was quite busy one would imagine), so, he improvised the grand introduction! I am not quite sure this was exactly the one we have nowadays but anyway.
I quite agree on the choir, a bit too short, but I think it to be one of my favourite musical moments, when the choir comes in, sings his verses and the piano seems to make grimaces in the background to distract the listener from the singer, as how to say: "Look at me, look at me!" Listen to it, just lovely!