It seems inevitable when you look back at how PubMed has lost control of its brand and purpose, but it's surprising to hear how deeply the irritation and sense of abandonment can run among users. At various meetings over the past six months that have included researchers, clinicians, and practitioners in various fields, the anecdotal evidence seems to indicate trouble lies ahead for PubMed for one simple reason -- users don't trust it as much as they once did.
The conflation of PubMed Central and PubMed seems to be the main factor eroding trust in PubMed as a useful filter for busy people. Users complain about too many low-quality results and the appearance of articles from journals they don't know or don't respect.
I've written about the many problems facing PubMed, including a confused brand and an unclear role in the information environs. While many people have been unaware of the specific problems and their sources, it seems that over time the effects of these problems -- low-yield searches, lack of trusted results, and equal or better alternatives may foreshadow a tide of user defections if problems are not addressed.