The button interface may drive you a little nuts at first. Rockbox doesn't use the play button to start a song/file from the menu screen. Once the song you want is highlighted press the "right" button instead of the play button. Same goes for selecting various settings. This was the one action that took the longest to retrain my fingers.
First thing to do download and try out some different themes. See
the WPS Gallery pageI got an iPod nano first generation at the end of November. Put Rockbox on it in December, and have been using it exclusively since.
Welcome to the Rockbox family!