Thoughts after reading "Lady Susan"

I've been reading a Penguin book comprising 3 Jane Austen stories: the novella "Lady Susan" and 2 unfinished novels "The Watsons" and "Sanditon". They are said in the introduction to cover 3 periods in Jane Austen's writing life: "Lady Susan" belongs to the 1st, a bridge between her juvenilia and her 3 1st novels "Sense and sensibility", "Pride and prejudice" and "Northanger abbey"; "The Watsons" belongs to the unhappy, quiet middle period; and "Sanditon" is her last work, interrupted by her death, concluding the period that produced "Mansfield park", "Emma" and "Persuasion".
As expected, "Lady Susan" is thin literally as well as figuratively. A few details seem contrived, and the ending is quite hasty and unconvincing, which I also feel about the endings of "Sense and sensibility" and "Northanger abbey".
However, it's interesting, and unlike any of her works. 1st, the book's written in the epistolary form (so was "Elinor and Marianne", but it was rewritten and changed into 3rd-person narration and became "Sense and sensibility"). A mingling of voices, "Lady Susan" shows Jane Austen's brilliant gift for employing different language for her characters. One can see that this form is limited and not the best choice for Jane Austen (especially when I don't even like her real letters, which I consider tedious, full of gossip and triviality, and which are probably read more for the woman behind them than for literary value), but it's nice to see her do something different. 2nd, Lady Susan is a deceitful, hypocritical, mercenary, scheming, shamelessly selfish and ruthless woman. Although such a figure appears several times, with variation, in later works, as Isabella Thorpe, Lucy Steele, Caroline Bingley and Mary Crawford, Lady Susan, unlike them, is a widow, and a mother (a future version of the 4 characters I've just mentioned?), and more importantly, she's the central, eponymous character and the driving force in the story. In the later works, immorality is rather concealed- such acts, happening offstage, are mentioned or retold briefly and the villains tend not to be seen in close-ups. Here, it is direct, the readers have Lady Susan's perspective and hear of her plans and have insight into a person who has neither conscience nor shame. 
Compared to Jane Austen's later 6 novels, "Lady Susan" is less polished, but for various reasons I think it should be seen in relation to them, for the reader's understanding and appreciation of "Lady Susan" itself and Jane Austen's works as a whole. The only regret is that she didn't come back to the novella and revise, it could have become another masterpiece, and a very unusual one.