If you're in the humanities, GoogleScholar's list of citations looks like a tempting way of quantifying one's impact on the planet. Or, at least, on fellow academics. However, I'm a bit concerned about the prospect of administrations using GoogleScholar's number count as a convenient shortcut, because GoogleScholar's number counts are frequently...odd. For example, here's my own profile. There are some weird things going on:
1) Wow, my edition of Robert Elsmere has fifty-one citations!
And amazingly, many of these citations predate its publication!
In other words, what GoogleBooks has done is simply attach all citations of Ward's novel to my edition, which is not helpful. (As some of you may recall, I had a long and ultimately losing battle with Amazon about their insistence on doing the same thing, which left me stuck with one-star reviews intended for entirely different editions.) I would guess that this is not an isolated instance.
2) GoogleScholar does not believe I wrote an article about movies, which deflates my citation count by, um, one. (They believe that the article exists, but don't have it attached to my profile. The perils of branching out, I guess.)
3) There are a number of "nonsense" entries in the publication list, including a book review of the aforementioned RE by someone else (it would be awkward if I reviewed my own work, you understand...), entries in journal indexes, etc. If one is carefully reading GoogleScholar, this is not an issue; if one is skimming GoogleScholar for quick data, however, it is.
4) Worse still, there are a number of "nonsense" citations, including, again, journal indexes, "books received," and annual bibliographies. Moreover, book reviews are sometimes counted twice (once on their own, once as part of a book review section). These are not "citations" in any sense of the term, and shouldn't be counted. However, to find them, you have to double-check the citation list for each entry, which is the opposite of a quick fix.
5) Finally, GoogleScholar is very spotty about catching citations in non-academic press outlets, which makes it difficult to detect impact outside a strictly academic audience.
Short version: be wary of GoogleScholar citation counts.