I use Zotero to manage the references for my PhD thesis, and export in BibTeX for use in LaTeX. It seems to work well, and is very handy for research being in the browser.

However entering multiple authors is a slow process in the current interface, you can't just type them all in one field separated by commas, but must create separate boxes to enter each one into. Easy to do, but time-consuming.

It is great for organising .pdf files. I have moved the Zotero library into my Documents folder so I back it up with my other work (you can select a custom Zotero directory in the Preferences dialogue), keep all my .pdf files in another folder, and create links from the Zotero record to each .pdf file. Very handy when you want to find a reference again.

Having said that I've found using any reference tool slows me down and I'm increasingly cutting out the middleman and just typing in raw BibTeX...