When we first began developing our C++ tools we wanted to see what usability issues developers would face so we ran a series of testing sessions with people new to Eclipse, people who had used Eclipse for Java development, and people developing with Visual Studio.
The bug 154280 has more details but my story here is that the issues on the front line have been addressed in Europa.
When we asked people to build a newly created project they looked for a build button in the toolbar. (The platform has a Build All button but it's not easily identifiable and it builds all).
Now CDT 4.0 includes a Build Project button that builds the active configuration of the selected project and has a menu that lets you build any of the other ones.
When we asked people to debug their project they naturally hit the Debug button and ended up getting confused by the Launch Configuration dialog.
Now CDT 4.0 takes advantage of the new debug platform support for contextual launching: Hitting the debug button now does what people expect, launching a debug session for the selected project and using the launch shortcut to ask for any settings it needs along the way.
We're tracking lots of other usability issues from C/C++ developers but I'm pleased these two big out of the box problems are fixed in Europa.