I have to say, the documentation is really quite bad for such a high profile engine. I realise that up until only a few days ago UE3 is purely a high profile developer engine, but now that it is free for non-commercial user I fully expect better documentation.
Granted, its an on-going thing. The biggest gripe I have is that the documention system is some archaic, locked-down, static system. Give the community a wiki so that we can freely edit and compile documentation.