Last week I finally decided to retire my Eclipse installation. I didn't remove it yet, since it might be useful for some specific tasks that I have deal with rarely (such as analyzing someone else's big C++ code). But I don't use it any more for my own work. Here's a summary of my impressions of Eclipse, the good and the bad.
However, in terms of usability it turned out to be a disappointment. Basically there are two major issues: Eclipse is a resource hog, and it isn't as stable as I expect an IDE to be.
The two resources that Eclipse can't get enough of is CPU time and disk space. Even on a brand-new machine (and not a low-end one at that), starting Eclipse takes a good ten seconds and I get to see the Macintosh's spinning colour wheel quite often. What's worst is that the spinning wheel prevents me from typing, at unpredictable moments. This is not acceptable for an IDE. I don't care if it takes a break in background compilation now and then, but I want to be able to type when I want. Execution times for various command can also vary unpredictably. Rebuilding all my projects took about a minute typically, but once I waited for 15 minutes for no apparent reason.
In terms of disk space, Eclipse is less of a resource hog, but it creates and updates impressive amounts of data, again for no clear reason. I noticed this because I make incremental backups regularly. Just starting and quitting Eclipse, with no action in between, resulted in a few MB of files to backup again. It's not that I can't live with that, but is this really necessary?
Finally, stability. I had only a single crash in which I lost data (the most recently entered code), which is not so bad for a big application (unfortunately...). But I had Eclipse hanging very often, and displaying verbose yet unintellegible error messages almost daily. All this is not reassuring, and together with the spinning-wheel issue this is what made me abandon Eclipse in the end.
Now I am a 100% Emacs user again, with no regrets. Emacs may look old-fashioned, and have some fewer high-powered features, but it is reliable and fast.