research process - What should a PhD student do when he receives no feedback on his work except some reviews on his papers?

I am consistently facing this issue: NO one (except some reviewers when I submit a manuscript) provides me with a detailed/core criticism of my PhD work.

My supervisor usually gives me general advice; sometimes he tries his best to understand and propose some trial-and-error approaches for the problem (most often I have tried these approaches before he proposes them). I simply cannot find someone who will smack me on the face and tell me the truth about my research.

After chatting with another PhD student, I found he has the same issue. However, he told me it is because PhD students have very specialised knowledge on a particular topic that makes it very hard – even for supervisors – to comment on it in a detailed manner. Well I still can't believe that's true in general.

So:

What should you do when you can't find smack-on-the.face feedback?