Amazon has now published reviews of all five of the tales. Again, note that these contain spoilers! But since none of us has a crack at the real Beedle the Bard anyway, this hardly seems to matter. How else are you going to find out what the book really contains? Unless you happen to have more than £2 million lying around.
Since that was obviously rhetorical, hahae, you’ll find the summaries here. I’d add that these are pretty detailed; one has to guess they’re almost as long as the tales themselves in some cases!