Hi
I beleive ST bought the company that produces Atollic Truestudio, which is Eclipse based. This will avoid having to install all the add on packages to get Eclipse working for ARM.
Personally, I hate anything Eclipse based. The way is does projects is stupid, it is based around directory structure, usually needing the base directory being "workspace". This makes creating multiple copies of the same project a pain. Then there is the bizare concept of where the Eclipse bases the project when you start the project, this can be somewhere completely different to where the "workspace" is and then it goes and creates loads of hidden project file there

Project files! God help you if your project files go wrong. Trying to fix them is near impossible.

Which retard thought forcing you to use tabbed edit windows was a good idea? Personally, I find it far more useful to arrange windows on my screen so that I can see all the defs, code without having to constantly switch tabs.

Rant out of the way.
I found Atollic to be buggy when debugging. It frequently froze and it was not clear whether it was Eclipse doing background updates or the target.
For target debugging I prefer IAR Workbench. Editor is not great but the debugger is rock solid.
Lauterbach is also en excellant debugger but there is no free version and it is difficult to use unless you know how.