This plugin made it easy to add custom styles to the TinyMCE editor. I loved the fact that buttons can be added to the visual editor, or the text editor, or both. Only downside is that you cannot choose whether to show buttons on the first or second row (currently adds to first row only).
My theme gave me trouble recognizing the css code I added in the button creator. I was able to correct by adding
!important to the css declarations. Not sure if this may be helpful to others too.