Whatever you're into, they'll probably have it - super high end antiques (fireplace mantels from…read moreold mansions, a whole-ass carriage, tons of 17-18th century furniture along with modern designer furniture too), jewelry, silver, vintage everything.
It's huge - several blocks, with more than a dozen markets, independent shops and more casual table top vendors. Do some research ahead of time so you know where to start because it can be overwhelming. There are plenty of quick cafes and places to grab a bite.
Here's what I found:
Paul Bert/Serpette - high end, mostly furniture. Some high end vintage clothing here too.
Marche Biron - middle of the road with lots of furniture and artwork.
Marche Dauphine - for the cool kids. Art, vintage clothes, records and some book/print dealers.
Marche Vernaison - a maze of more than 100 dealers. This is the best place to find smaller, reasonably priced things to bring home. I enjoyed this market the most.
Overall - if you have time and are willing to make a big of a trip, this can be super fun. The metro is an option but the 85 bus drops you right in the market and saves you dealing with the sketch "thieves market" between this and the Metro.