Erik tried out both IDEs this weekend, and decided IDEA has the upper hand:
I spent most of the weekend refactoring jTalk's various Utility-type classes, which was long overdue. In the process I got to seriously play with Eclipse and IDEA.
I've used both before, for smaller projects; never with anything really sizable. As I was telling Russ last week, I'm an old school kinda guy. You give me vi and I'm happy as can be. It is hard to break old habits... Nevertheless, I was not looking forward to hours of endless regexp substitutions.
When it was all said and done, I have to admin I would give IDEA the higher mark.
Both are excellent, feature-rich IDEs. I was easily able to do anything I wanted to in IDEA, but I did have to refer to Eclipse's help and FAQ quite a few times.
CVS support is stellar either way. Although I find IDEA's color labeling more intuitive. Ant is also well integrated in both products.
Eclipse (out of the box, sans-extra plugins) lacks extended support for numerous file formats (xml, dtds, tlds, etc.) On the other hand IDEA was able to handle just about anything.
Performance wise, Eclipse is a little snappier, but nothing extremely noticeable. Visually, Eclipse is more appealing, but not more functional. The IDEA sidebars are extremely useful.
In the end what annoys me the most about Eclipse is that I keep on having to look for menu items, settings, etc. In IDEA, everything is where I would except it to be. Maybe it's just me, the way my left brain works.
Okay, I will admit IDEA is pretty awesome. I like its flexibility (no projects to import like in Eclipse) and its intuitiveness. HOWEVER, I have to say that there's NOTHING like the CVS support in Eclipse. I've used it in anger and I can say without hesitation that it is the best CVS client that exists today. It rocks. As for Erik's other issues, it takes 30 seconds to download and install the plugins you need for XML highlighting, etc. so that's not a real problem. On slower machines like my PIII 650Mhz/256mg RAM at home, Eclipse blows IDEA away both on performance and memory usage. Eclipse is also free - so wins on the price/performance contest hands down. There's also more and more tools available for Eclipse every day, so it's got a real future.
I like IDEA and have used it before, but I've switched to Eclipse wholeheartedly and am quite happy with it despite its ugly spots. I've said this before, in my opinion, IntelliJ needs to scrap it's proprietary IDE and start making plugins for Eclipse. That would rock.