1. Rating
   Rate the paper in the following categories (For each category,
   choose a one numeric rating)
       
   Overall grade (overall, how do you rate this summary paper?)
      4: Very good

   Language (how fluent is the language, did you understand what this 
   paper is saying?)
      4: Very good

   Technical quality
      5: Contents are completely correct. There are no errors. It corresponds
         information on the source material. 

   Editorial quality
      3: Understandable with some effort, several improvements suggested
         below

   Confidence (how confident are you about this review?)
      1: This is a completely new subject to me; I made educated guesses


2. Detailed comments

Paper provided a good overview of different time synchronization methods.
Since attacks have been mentioned in the paper, it would be good to mention 
methods (or lack of methods) of defence against those attacks. Advantages and
disadvantages of various protocols could also be mentioned more clearly.

Some miscellaneous issues:
- All figures should have numbers (now only the first figure has a number) 
and they should be referenced and explained in the text.

- Chapter numbers would make the paper more clear, now it's a bit difficult
to notice when the next top level chapter begins.

- page 6, beginning: "a message is broadcast to two receivers"
should be "message is broadcasted"?

- page 6, middle, reference missing? "more on this method can be found at 
... some reference"