How valuable/impressive is a review article written by an undergraduate? I am the Graduate Coordinator of my department at my state research university.  I am currently evaluating several PhD applications for a prestigious internal fellowship.  The catch is that, while I am in the math department, I am only evaluating applications from other STEM departments.  When it comes to accomplishments in the laboratory sciences, I am often out of my depth, and I usually just admit as much and move on.  However, I've just come to something in which I wonder whether academic cultural differences could give me the wrong idea (rather than no idea).

Namely, an undergraduate student in chemistry has written a review article under the direction of a faculty coauthor. The faculty member says of the student:


  [S/he] was
  responsible for assembling the preliminary bibliography and writing the initial summaries of the
  main papers that we reviewed.  [S/he] was primarily responsible for creating the schemes and
  figures used in the paper. While I did have to heavily edit [his/her] writing, which is to be expected, [s/he] really carried a bulk of the work. Consequently, [s/he] is first author on this paper.


(I did look at the article, but I won't violate confidentiality by describing it...and moreover I am completely incapable of meaningfully evaluating it.) 

My question: how valuable/impressive is it for an undergraduate in chemistry to be the first author of a review article like this?  By way of comparison, in mathematics there are almost no "review articles." The closest equivalent I know of are long articles published in the Bulletin of the American Mathematical Society, which are more like historically oriented mini-courses on a mathematical subfield written by a leading expert in the field.  This type of review article strikes more as a helpful library tool for a chemist interested in certain types of reactions and procedures. So it looks more like a moderate piece of service to the profession, and being first author sounds like the student carried out the assigned task more independently than not.

Is that accurate?  Or is it a big plus for an undergraduate to have done work like this?
There are several factors to consider here when evaluating the "significance" of a review article:


The length and scope of the review article: a six-page review of recent literature with 50 references is not as impressive as a 50-page review with hundreds of references.
The publication in which the article appears: is the journal a high-level, review-only journal, such as Reviews of Modern Physics or  Chemical Reviews, or is it a review article in a traditional journal?
Was the review invited or contributed?
Is it part of a special issue? (If so, the standards for acceptance are often a bit laxer than in a "regular" issue.)
Since it's written as an undergraduate, you might try to compare its citation count to similar review articles written around the same time as a proxy for its significance to ongoing research in the field.