When I was a child, my father - who could not read music but loved it - used to tell me the basics of musical history, including how the Eroica ushered Romantic times into symphonic music. Having seen this film on TV, I decided to purchase the DVD, and I am very happy to have done so.
I agree with SOME of the criticisms by Nicholas Casley: everything is SO English, especially the acting! And certainly this is a product for the classical-music lover.
However the important matter for me is the performance. This recording by Gardiner and his orchestra is the best I have ever heard. It is indeed a bit too good for a first reading at the time, though I can hear a few very authentic mistuning of a double-bass and others. Most importantly, the reproduction of a performance in Beethoven's time is incredibly accurate, down to the role of conductor and leader, scarcity of vibratos in wind instruments and many other matters of historical instrument sound, speed, balance and phrasing. These are not just details, but an important part of the work as conceived by Beethoven: they make the work sound much more coherent, convincing and moving.
I take note of the discrepancies Casley finds between sound, orchestra and venue. Nevertheless, I find this the most careful and beautiful reproduction so far of how Beethoven wished to hear his Eroica: close your eyes and you are literally there and then. Well done Gardiner and the Orchestre! The drama around the performance adds interesting historical and personal inputs to this vision of a masterwork that indeed changed the history of music.