I'm a big fan of Eclipse; I think its full of great ideas, and is a big gift to the larger community. It gets the job done quite well. And it's free.
However, there are quite a few rough spots.
One thing I hit quite often is mysteriously locked files. I see this most often when updating or replacing my directories from SVN (and sometimes CVS). Often, an update will fail with some kind of locking error on the local file.
Sometimes, I have the file open in another window. I close the window and the process works. Less than ideal, but I can live with it.
Sometimes, I don't have the file open and I still get the error. My working theory is that Eclipse has it locked, perhaps due to indexing. Often I have to restart Eclipse to get the lock to clear!
Am I the only one who experiences this?