i think it's an essential part of the welles collection, and it's darn good. i've read some here no liking it much, but like anything else, you gotta look at it and make up your own mind.
the scraps the documentary shows of what welles did with color film is breathtaking.
to me, it's all true documentary belongs on the first shelf along with kane, ambersons, and journey into fear. it's a very important period, and it's a very good documentary. you might also put on this shelf the welles segment of the rko story, it covers the rko years.
one of the producers of it's all true, myron meisel, also did the SAP for the voyager othello, and i think it's the best commentary on any welles film. even better than ebert's on kane. though ebert's commentary is excellent.