How to deal with "too descriptive" comment in dissertation proposal feedback?
The difference between descriptive writing and critical writing is much like the difference between a newspaper report and an opinion column. 

Descriptive writing is the act of reporting on what's in the literature: 


  Smith found that when X occurred Y and Z also happened.


Critical writing analyzes what has been done, and takes note of trends, as well as possibly offering feedback on the overall quality of the research: 


  Smith found X occurred in the presence of Y and Z, as did Jones. However, Doe has demonstrated that Y and Z normally occur in conjunction with one another, so it is not clear if X actually influences Y and Z, or if it is an independent effect.


What you can see from the above is that critical writing does require some descriptive writing, but it goes well beyond it in terms of the depth of analysis.