R. v. N.M., 2012 ONCA 296 gives a useful treatment of an appeal court’s review of a conviction for reasonableness:
 This court has the obligation to review the reasonableness of convictions: Criminal Code, s. 686(1)(a)(i). In exercising that authority, the court must, to some extent, review both credibility assessments and factual findings made at trial. It does so, however, bearing in mind both the advantaged position of the trier of fact and the limited scope of review. The question for the appellate court is not what it would have decided, but whether a properly instructed trier of fact could reasonably have rendered a guilty verdict: R. v. Biniaris, 2000 SCC 15,  1 S.C.R. 381, at paras. 36-42.
 The reasonableness review provides an important safeguard against miscarriages of justice. In Biniaris, at para. 42, the court described the nature of that review in these terms:
To the extent that it [appellate review] has a subjective component, it is the subjective assessment of an assessor with judicial training and experience that must be brought to bear on the exercise of reviewing the evidence upon which an allegedly unreasonable conviction rests. That in turn requires the reviewing judge to import his or her knowledge of the law and the expertise of the courts, gained through the judicial process over the years, not simply his or her personal experience and insight.
 I understand Biniaris to instruct that the knowledge gained through the reviewing court’s broad exposure to the criminal process provides insights into credibility assessments and fact-finding not available to jurors whose experience is generally limited to a single case. Those insights must inform the reasonableness assessment.