Both Hugh Grant's Music and Lyrics and Leonardo di Caprio's Blood Diamond are well worth watching. In their respective (and of course very different) ways they deliver what they promise.
On the other hand I was very disappointed with Patrick Stewart's (and I am a huge fan of him) Antony and Cleopatra. 1-dimensional and 'read'. Where was the acting?
Whatever you do: set expectations and deliver. At the very least.