The first review is complete and utter rubbish!
Delcampe is a seller site similar in some respects to eBay but not as tightly regulated. For example a seller dictates which payment methods are acceptable - so if you do not want cash or Paypal or whatever you can indicate what is acceptable or not.
It is a far friendlier community than eBay and does not have the same level of fee gouging that eBay has. If you are a buyer or seller of collectible items such as stamps, coins, banknotes and the like you will find a huge choice. As with all internet buying one does need to use common sense and check things like a sellers terms and conditions, acceptable payment methods etc. BEFORE committing to buying not afterwards.