Am very new to Birkenstocks.  Feet really developed problems from flat sandals being worn all summer. Knees, arches and sides of feet were in pain. Birkenstocks were recommended to me so I tried. Felt and looked strange first day or two. After a week they feel great. I wear these and feet & knees  no longer hurt at all. Still getting used to the look though, but comfort I am sure will outweigh doubts.  I am really happy I bought these. Just purchased 2nd pair in different style.