I made a few orders without any issues and at first, was very satisfied with the service. However, I regretted buying from them when I needed customer support for the first time. I ordered shoes but they were too small for me, I tried them out and wanted to return them, but they did not want to take them back. They told me that it was their policy that they could do so, which is strange for some EU companies. If you are selling flagship shoes for hundreds of euros I would expect at least minimum care for your long-time customer but well... You will not get that with 21run.com. Buy somewhere else even if it's a few euros more expensive...
Strengths
Good and easy-to-use website
Improvements or tips
Improve customer service