If you have installed R in your Ubuntu and you need to some machine learning work on it, Rattle is recommended.
You may met problems when installing RGtk2, like this:
GNU/Linux: configure: error: GTK version 2.8.0 required
This error occurs when attempting to install the RGtk2 package. The install is looking for the header files for GTK. Possibly they are not yet installed on your operating system. For Ubuntu and Debian, this is easily solved:
$ wajig install libgtk2.0-dev
A photo with the author of R-Rattle, Dr Graham Williams, on the Sixth R Meeting in China: