This was my second time watching Masked and Anonymous. On my first viewing it didn't seem to be as bad as some critics had made it out to be, but after a second viewing I have to agree, it's pretty darn bad. Written by Larry Charles and Bob Dylan (using the pen name Sergei Petrov) the dialogue is heavy-handed and juvenile trying to deliver "important messages". Dylan's acting is so bad, that even though he's basically just playing himself, he can't seem to pull that off. Bob surrounded himself with a great bunch of actors, all working for scale in order to be in a film with Bob Dylan. Unfortunately, having a great cast of good actors just made Dylan look even worse.
The plot, such as it is: In a dystopian future Jack Fate (Dylan) is in prison, but is released to do a benefit performance. As Dylan proceeds to the concert site and prepares for the show, we meet a variety of characters, all played, for the most part by famous actors. Dylan sings several songs (the oddest of which, to me, was "Dixie") and the soundtrack provides more Dylan tunes covered by different artists. As noted above, this movie seemed to be striving, but definitely not succeeding, in providing some message about politics, or society, or Dylan himself. Your guess is as good as mine.
Most days I'm a Dylan fan (probably why I didn't think this film was so bad on my first viewing), but I consider this movie to be one of the lower points in his career, even worse than his Christmas album and his Sinatra covers album. If you want to see Dylan in a movie, I would recommend "Pat Garrett and Billy The Kid", where Dylan actually acts, or even the laughably bad Hearts of Fire, which is still better than Masked and Anonymous.