Plot-wise, a series of comic melodramas around inheritance and romantic relationships (for love's sake and inheritance's sake).
The round characters are mostly likeable (Elinor, Brandon) and the flat characters are mostly unsympathetic (Lucy, Robert), with some exceptions on either side (Willoughby, Mrs. Jennings).
Austen's morality is tempered, which fits given that comedy generally tends to be conservative (in nature, not politically). Some of her characters behave badly, but she doesn't feel the need to punish or redeem them. Robert cheats his brother and they end up (mostly) happy neighbors. The good characters get over the bad done to them, things work out somewhat better than we expect and everyone muddles through. There is a general argument for moderation: Elinor's patience with Edward, Marianne's zeal and later humbling, the narrator's similarity to Elinor (herself moderate).
This is one of those books with a lot of characters where it's hard to keep everyone straight. I plotted a family tree for the Dashwoods and Ferrars but couldn't keep track of the Steeles and the Palmers enough to do so for them.
The book is very funny and its humor reflects its morality:
The whole of Lucy's behaviour in the affair, and the prosperity which crowned it, therefore, may be held forth as a most encouraging instance of what an earnest, an unceasing attention to self-interest, however its progress may be apparently obstructed, will do in securing every advantage of fortune, with no other sacrifice than that of time and conscience [page 370]