It seems that if we were in regular time, Liz always had something going on that made her different from her normal self. Fortunately for us, when we were in different time period, JB was always given good roles to play. I actually like her period roles better than later Liz. Early Liz is, of course, always a joy to watch.
Liz was the woman who was in charge of her home yet had lost control slowly over time, due in large part to her own paranoia. Then she became bland and was put under many spells. If you think about it, all of the other characters JB played were an extension of Liz:
Namoi was a rich character, not at all unlike Liz. Naomi was loving towards her children, and tried to set her family on the right path, but was largely opressed by her husband who couldn't be bothered with her "trifiles", which drove her to drink herself to death (among other things).
Judith was yet another extension of Liz, but instead of being the losing side of the coin, Judith was on the winning side, at first anyway. She was powerful, determined, and yes, even a bit vindictive and greedy, but what Collins isn't? She ruled her home with an iron first (much like early Liz), and made sure everything and everyone were in their place. And, just like Liz, she was brought down by a lying piece-o-crap of a man.
We also had Flora, who was perky and naive, never really grasping what was going on. Flora could probably be likened to a younger, teenage Liz, though I like to think that Liz was smart even when she was young. Flora is probably the least-like Liz out of the three character I've mentioned. Actually, Flora might be what Liz would've been (maybe not as perky and naive, but somewhere inbetween) if Liz didn't have such a rough life.
So, really, we did get treated to Liz, quite a few editions of her, and we got to explore a number of different sides of her personality through these various characters.