If you're into paying too much money for corrupted or half-hearted takes on Modern classics, Rubin's is the furniture store for you.
Aside from a couple respectable lines, such as Herman Miller's home products, most of the pieces are from second-tier brands or non-brands and priced at levels you'd expect in a town with no other good or large-scale alternatives. Many of Rubin's furniture is not so much designed as styled. If you squint, it looks decent, but try to get a close look at the aesthetic details and build quality before buying.
I would recommend anyone interested in well-designed modern furniture to feel free to browse Rubin's, but to try online options before buying. Good alternatives include Design Within Reach, Ikea (similar quality to Rubin's, but a lot cheaper, and often better design; nearest brick-and-mortar store is in Schaumburg, IL), the Museum of Modern Art online store, Topdeq, West Elm (limited but sometimes worthwhile), Chiasso (hit or miss). If you're really looking for high-end contemporary and have the funds, I would recommend a trip to Luminaire in Chicago.
Rubin's does have a store on the west side of Madison specializing in Scandinavian design which may be a little better, though I would recommend people who are into that sort of thing check Century House on University Avenue by Shorewood, first.