Something I would like to see is a one-page (or less) summary of the character creation process. I'm not 100 per cent sure, but I think there is no such thing in the PG. This list should include all steps necessary, as well as the page numbers of the required chapters.
Another thing I'd like to have are rules for creating unjoined Trills. Most Trill aren't joined, and Ezri is living proof, that even in Starfleet there are unjoined Trill.
A IMHO great flaw that could go with that would be Jealous: the player has to make a ??? test, every time she could make life harder for a joined member of her species.
I could live without the flaw, though. Somebody pointed out to me once, that due to the reverred status of the symbionts in Trill society, such behavior would be very unlikely. This argument hasn't really convinced me, but maybe that's just because I'm human and not a Trill.
“Worried? I’m scared to death. But I’ll be damned if I’m going to let them change the way I live my life.” - Joseph Sisko - Paradise Lost