One more suggestion: as sometimes we have the DOI handy, but importing directly via DOI leads to the aforementioned problems, and sometimes no abstract, although available, it may be worth thinking about a way to retrieve from PubMed by using the DOI (and not PMID).

One simple way (from the user point of view) to implement this would be to allow inserting a DOI in the PMID field. When hitting search, if it looks like a DOI (two digits, period, some other stuff), then search PubMed not by PMID but by AID (article identifier). Once found, the fields are populated as usual, and the DOI is moved to the DOI field and the PMID is filled with the PMID, instead of the pasted DOI.

Bump!
Why in the world does the script have to be case-sensitive? That it has to be a perfect match is clear, but the case-sensitive is a PITA. There are plenty of instances when importing into Mendeley leads to a journal name in Title Case.

Two examples:
10.1111/j.1365-2133.1970.tb12440.x and
10.1016/j.jaci.2003.12.583
Using Mendeley Desktop -> Add Documents -> Add entry manually... -> paste DOI and lookup you get the journals as
Journal of Allergy and Clinical Immunology and, respectively
British Journal of Dermatology

I don't think there's much Mendely can do about, since I presume that's how Elsevier and Wiley serve the citation; importing via PMID renders the journal names as it should "The Journal of allergy...." or "British journal...".
Obviously, the first case does not get abbreviated, the second gets.

I have about 500 references which should be changed now, some since they were not properly imported and others since they were exported from another ref mgmgt software as RIS with Title Case.

So, why not making the script case-insensitive, or at least providing an option/switch to make it such??