The move of the Notes Client to an architecture based on Eclipse is seen as a good move by most people. Recently, though, I ran into an issue that you might need to be aware of. One of the other applications I use to develop web applications is Aptana Studio, which is also built upon Eclipse. I hadn't been in it recently, so when I fired it up last week, it asked me to download a bunch of new updates. Halfway through the installation, it failed because it wasn't able to access/update a certain .jar file. The worst part was that the failure completely hosed my configuration and caused the application to be unusable.
After much debugging, I determined that the install failed because I had Notes 8.0.1 running at the same time. After blowing away the configuration and shutting down Notes, I was able to successfully upgrade Aptana to the latest release.
So the lesson learned is to make sure all your Eclipse based applications are shut down before you try to upgrade one of them.