So there are two things that really make these books special, the perfect capturing of the way people interact in their own little social groups and hangout with friends together with this sort of deadpan satirical humour that's not really designed to make someone laugh out loud but creates smiles at the exaggerated absurdities of people living out their lives.
It's roughly there that the similarities end (but was there anything more important than they can share?), the now fantastical feel of high society British society is replaced with fantastical elements from pop culture made real and it's used to show how the characters think about the world. Instead of balls and carriages, it's boss battles and bass fights. If you can't delight in the characters cooking a Vegan Shepards pie (no-ones vegan, they just like to be inclusive) including one of the characters giving you the genuine recipe, maybe it's not for you.
But the most important difference is where they decide to stop. Jane Austen
novels always end with the reveal of love and the happily ever after marriage, but the declaration of love is only half the story in Scott Pilgrim
, relationships need to be worked through and how people get over their problems and share each other is just as much part of the story as how they first got together. In general the books have a sense of time and pacing that few other things have been allowed. There's touching, heartwarming moments of character growth and realisation that happen in book 3 whereas for any single book or film they'd have been saved for the epilogue. People get better and relapse but with a bit more knowledge and keep on moving forward.
Books 1 and 2 represent best whats to come, they have the quirk and romance and humour that you can expect although being introductions the drama hasn't reach it's peak yet.
3 and 4 are by far and away my favourite, relationships have really consolidated and the arc with Envy Adams is so central to the overall story, a lot of the most enjoyable and touching moments are in this arc.
5 and 6 are much darker and in many ways can feel like people have regressed too much. But reading through them again as part of the series, although they struggle to bring everything to a close with the weigh they added, everything that should be there is and they do a fine job and bringing the series into context.