They also come in "regular" leathers. I tried on a Chocolate Epsom 25cm Birkin with GH. Definitely not for daily use, but perfect for special occasions or for occasions where a larger bag would not be suitable.
I know it's not the same thing, but I had a LV PM Reade, which is about the same size. And I used it to DEATH!! It was perfect for night and day. Day, as long as you don't overstuff it. Some days I just have my wallet, sunnies, keys, tissue paper, lipstick, compact and it all fits in nicely. These days I bring a book everywhere I go, plus a calculator and a bunch of not-really-necessary-to-lug-around things. But when I get my Hermes bags, I don't think I will abuse my bags like that anymore.