Design reviews are essential checks on the design process.  I have never been at a good design review where there wasn't a useful discovery made.  As a boss of mine once said, if one gives an engineer a chance to make a mistake once, he will make the same mistake over and over again.  I have found this to be true about undiscovered mistakes.  Design reviews are the forum by which one discovers mistakes in one's work.  

The other way design reviews improve designs by exposing them to different engineers is more predictive.  It may or may not  be obvious to a circuit designer that it will be a mistake to run the 10MHz TTL square wave right next to the high impedance input to a high gain amplifier, but it is great information to have mentioned at a design review.

I offer design review preparation services that include circuit description, uncertainty analysis, component sensitivity analysis and layout recommendations and EMC guidelines.  

I will also look over your prepared design review package, look for holes in the documents and offer my thoughts if you would like a pre-review review.  I know some firms have folks who take undue joy from making a colleague look unprepared during design reviews.  I can not guarantee that I will see all of the flaws that some of these professional fault-finders will see, but I will certainly look for them.  My goal will be assuring that your design is robust, not assuring that I look smart in a meeting.