A genuine attempt smothered with Hollywood cheese

Agreed.

I still found it pretty powerful. Perhaps would have worked better with real people, but then would they have been the same if filmed?

If it had been fiction I would have agreed with you, but the fact that it was real made it powerful, and I don't think the soundtrack or the acting detracted from it too much. Although ironically, it was the actors that I didn't recognise that I thought did better than the "names".

I think that the format is really interesting....someone on another thread said that movies that are 'documentaries' are usually comedies (mockumentaries) but this one wasn't.

Also...whereas as it WOULD be interesting to see the real people, let's face it - if this were a straight-up documentary, it likely would not have had as large an audience. Sure, things like March of the Penguins and Fahrenheit 911 were big successes, not just for being documentaries but for any movie, really - however these are exceptions, not the rule.

And, as others have pointed out, the interviews were audio recordings which formed the basis of Moises Kaufman's play....of which this is film version. It would not have been possible to make this movie the way you want. Isn't it better for the story to be told at all, even if it might not be told in the "most effective" way?

Agreed. Unknown actors would have worked much better.