Watched this earlier today - A little something from Santa...
http://www.sennamovie.co.uk/I thought it was very watchable and well made.... made even more enjoyable because my interest in F1 began just as Ayrton was arriving in the sport and I can still recall (sometimes vividly) some of the main events in his F1 career.
I remember being galled by his (later admitted) deliberate attempt to take out Prost in Suzuka to win the 1990 FI championship. Being a Ferrari fan I only had eyes for the prancing horse but the film does put a slightly different viewpoint (from Senna's perspective). At the time he was the villain in many people's eyes.
Other aspects include his marked superiority in wet races and the sight of his yellow helmeted Lotus (black or yellow) or (red & white) McLaren bearing down on Ferraris ahead almost always had a depressing inevitability about it.
Later in Imola, the scene of his fatal crash, the whole weekend was a disaster from Friday to Sunday with spectacular (Barrichello) & fatal (Ratzenburger) crashes in practice followed by a startline rear end into a stationary car (non fatal) & Ayrton's unexplained straight ahead crash.
Overall, I would highly recommend it...