Should I write a peer-review in third person?
I recommend the first person.  Like most good linguistic constructions, the reader passes over it without explicitly noticing it, whereas your first construction with &quot;this reviewer&quot; holds up the entire mental process for a split second.
The idea of using the third person to &quot;soften&quot; the criticism: well, Paul Garrett knows how much I esteem him, and we usually see eye-to-eye on things.  But this time I simply disagree.  The reviewer is empowered -- nay, enjoined -- to supply an opinion on the work.  If you want to shade your opinion, explain very carefully and explicitly why you are doing that.  Switching to the third person should not convey that you are less sure of yourself, and it does not convey that to my ear.
[Imagine my answer began with &quot;This academic&quot;.  Wouldn't that have been more distracting?]