I initially was very sceptical of Eclipse E4: in a lot of ways it smelled like design by committee. Eclipse's main problem has always been its heavy coding style (factories everywhere, downcasts, code snippets that expose the innards of the platform, hard-to-reach service objects, etc.) and it seemed like E4 was continuing that trend.

Thankfully, the latest information on E4 paints a more positive picture:

• I have been thinking a lot about how to write applications that work well as both web applications and as a desktop applications. E4 is trying to go in the direction of a universal platform. I used to think that this was just a gimmick (as most multi-target GUIs, that I've seen, are), based on their preference of RAP. But it turns out that they are considering all kinds of options, including GWT, Bespin, and Flex.
• The E4 team also reported that, when cross-compiling to other platforms, the snippets are a major hindrance and thus will probably go away in the long run.
• They really seem to be eager to remove some of the cruft. For example, dependency injection is going to work wonders for discoverability of the API.

More information:

• Talk on E4 at EclipseCon.
• Eclipse wiki. Especially the slides on the future of SWT (warning: zipped ppt file).