Oh, they're crowd-sourced internet UGC - of course they're subject to manipulation. But frequently having something is better than nothing.

I think it's ultimately a positive thing to have a mechanism for users to flag content as being questionable and have that flagging be subject to some kind of court of public opinion.

If anyone spends much time on Wikipedia they're familiar with this kind of public debate. Community Notes are a bit like a less sophisticated Talk page. Obviously it's imperfect and obviously ideological shades leak through, but it's still better than forum-style god-mod autocracy.

They are. The "proposed" ones you see if you are a CN moderator show you all the crazy, biased ones. Those then get whittled down to the ones you see. The published ones are generally high-quality, with a small percentage of wrong or bogus ones.

The algorithm is specifically designed around manipulation resistance. You could think of it as being sort of like the difference between mob rule and trial-by-jury.

Certain users were handpicked to be able to write community notes. Nobody else can.