The idea is that Evernote, like every other tech company, uses algorithms to aggregate user data. This is then shared with partners for a variety of purposes, most of which are concerned with advertising.
What is different in this case is that Evernote isn’t confident in its algorithm’s ability to properly parse the information, and wants real humans to double check its work. This is where the potential invasion of privacy could happen. Needless to say, the reception to the announcement has not been pleasant.
For now, Evernote claims that only a small number of employees will be able to access user information, and those that are given the privilege will be subject to background and receive training. Of course, this still allows strangers to read private notes; or worse, confidential business information.