I made my students in IT 669 use "some principled way" to keep up with their references. Most of them had not started using anything, even a word processing document that they could copy and paste from.

I figure EndNote must bye really, really bad, because I don't think I know anyone who really uses it. I'm a BibTeX guy myself, and though I wouldn't recommend it to anyone, I can't use anything else. I'm working on a lit review now and accidentally found RefWorks, which I think I like better than EndNote (but to be fair, it's mostly because it's web-based, so it works with Linux, and it does decent exports to BibTeX).

In IT 669 one of my students did a survey of students to see if and whether folks were using something like EndNote, and most weren't (it was a small sample, and somewhat skewed since many of the respondents were in my class). My take is that few people use EndNote for formatting refs, and that a few more use it as a database. From what I understand APA's format is so rife with stupid inconsistencies that EndNote can't really do APA refs correctly.

But really, keeping stuff in a database is something that has a learning curve, and most people are unwilling to do that. I argue elsewhere that one problem with programs that are easy to use is that people often are discouraged from learning to do things more efficient ways.