Yes, yes, a thousand times yes! Lady Susan is grossly understimated. You rightly point out, Sunnie, that it is very different to the six narrative novels. The traditional Janeites have never understood it; it makes them squirm; they are only too happy to relegate it to the Juvenilia, where they can safely ignore it and pretend it isn't the real "Auntie Jane".
Let's not be polite about it: Lady Susan Vernon is a toxic, middle-aged, vindictive, vengeful, lying, sociopathic bitch. Not your average Jane Austen principal female. She will take sadistic pleasure in crushing the spirit of her own daughter. She feels only contempt, and would love to humiliate, those who have helped her in her times of distress. She is afraid of Cath Vernon, because Cath is the only person who can see her for what she really is. At the end of the story, she succeeds in entrapping a rich fool; nevertheless, she will probably end her days in a sheltered environment, a destitute, psychotic slut.
Does Lady Susan Vernon really believe in her personal universe of "alternative facts"? It's very difficult to tell; sometimes she seems self-aware, but most of the time she seems to be a prisoner of her own web of deceit. This ambiguity, this uncertainty as to Susan Vernon's real state of mind, is not due to Jane Austen's teenage immaturity; on the contrary, it represents a triumph of artistry, as I hope to show in a moment.
Lady Susan is indeed very different to the six narrative novels. In its own way, it is not inferior to any of them. Jane Austen did tend to verbosity a little bit; she had to cut P&P extensively to fit it for publication; there are passages in Emma, and Mansfield Park, which could have been trimmed. But just try it with Lady Susan. There is hardly a letter, and within each letter, hardly a sentence, which could be safely deleted.
In arriving at a proper assessment of Lady Susan, part of the problem lies in the perception that it is the production of a teen-age mind. People assume that such a mind (even if the owner's name IS Jane Austen) could not really produce a masterpiece. But Lady Susan was not the production of a "teen-age" mind. Conceived in c.1794, when Jane Austen was 18 or 19, it was only completed c.1806, when she was at (or approaching) the height of her creative powers. And that changes the game.
Lady Susan is Jane Austen saying to the world: this is me, unplugged. If it makes you uncomfortable, well, f**k you.
