PFO's are hard to write, no matter what the venue, so it's best to be completely honest. I know this sounds harsh, but be as accurate and as detailed as possible in your writing. If you don't think it will "appeal" to the audience, tell them, even if it means telling them that this or that is lacking in chops, whatever instrument or voice. Better they hear it up front, so they can progress. The only way they/WE can progress is through CONSTRUCTIVE critique. Some bullshit about some bullshit doesn't help anyone... been there, done that, had it done to me. It's better to be honest than to try to avoid hurting feelings because it only delays the inevitable.... screw the Beetles and Harry Potter... honesty and clarity are the best policies.