A problem I found with Chrome's current implementation is on pages where you don't even know flash is being used, Google Translate and Soundcloud for example, after thinking the site was broken I remembered I had click-to-enable active.
Indeed, this happens to me too. And I think this is why Mozilla will need to have a very good UI to tell the user how to fix a broken site (or just fix it for them e.g. through a crowd collective).
