First off, it's also a store in L.A., called Tini which I'm dying to shop at!
Secondly, it is a vast selection of home decor items that are gently used, retro, mid-century, eclectic, industrial, vintage, modern... basically all the best. What I really like is how user friendly the website is, with items categorized not only by department, but by color, room, and/or style.
Like any great thing, with success comes a higher demand, and therefore higher prices. Some of the bric-a-brac is listed as a higher ticket than what I would dish out for say, an ashtray, at the same time some of the larger pieces are reasonable considering their condition, for instance this set of pretty dressers for $195 each.