What is "unique" about them is three things. They take a very keen edge which lasts a very long time and they are very easy to hone. Also, these qualities are consistent throughout their line.

They were mainly used as professional razors and barbers loved them. As a matter of fact their reputation came about because customers would ask barbers what they were using and in many cases it was a duck.

Like with anything else you have to decide for yourself if the item is worth the asking price.