I had a similar pair of Birkenstocks which I used for years, watching them fall apart, but still wearing them around the house.  I've never bought shoes online so I was a little leery about doing it, but since I was having a hard time finding Birkenstocks in stores, I decided to take the plunge.  I am very happy with the sandals I bought.  The arch support in this sandal is superb and it just feels healthy to wear them.  I also like the back strap.

My only criticism would be in regard to sizing: my feet are a size 9 which equals 42 in European measurements.  I was given the choice between two different 42 sizes, and the significance  was not made clear to me.  In the end I am very happy with what I got.