I definitely noticed that her character fluctuated quite a bit over the course of the 6 seasons (not quite as accurately as you did), and i was quite tolerant of her for the first few seasons, but it was her 'final form' that i really couldn't stand. I swear there were entire episodes where she did not say one serious thing.. I mean i'm all for a character that lightens the mood, but with her it just seemed relentless. This was also hard to reconcile with the fact that she's supposed to be the product of 7 lifetimes worth of wisdom and experience etc.. she's basically just a smartass?
TOTALLY. She's supposed to be wise, not a wiseass. I remember in the episode where she and Worf are slogging through that jungle planet, and even when she's seriously injured, all she can do is crack jokes (and not even good ones), I kept thinking, "Why is Worf WITH this woman??"