I watched the first half and dvr'd it to watch the rest this weekend. I thoroughly enjoyed what I've seen so far. Didn't make me much enamored of Ginger Baker, but the insights into Cream, Blind Faith, the relationship with Clapton and Jack Bruce and the mid-to-late 60's British music scene were fascinating. I grew up listening to my older siblings' Cream, Blind Faith, Bonnie and Delaney and early Clapton records, and have always loved that period of British music, so for me Beware of Mr. Baker was a real treat.
Ginger Baker came off as a bitter old man, and I didn't find him the least bit likable, but there's no denying his musicianship in those early days - he was brilliant. He did claim to have beaten down Jack Bruce and threatened to stab him, but didn't (at least in the first half.)
I'd highly recommend the movie to anyone who follows British blues rock.