It is hard to say anything general about vintage as it covers so many different styles and ages, and it also depends on the condition of the clothes, but if it is nice I think it can be an important part of a wardrobe. It gives you opportunity to add something to your looks, which you can't make with only contemporary clothes.
My grandmother had a shop from the 1930's until 1971 where she sold some luxury clothes and I am very happy for having inherited the surplus stock. I use the dresses often.