Gradient fills are typically blended fills between two or more colors that graduate from one color to another. Text filled with a gradient can look great or gaudy depending upon the type of gradient you use for your text. There are some more guidelines that will help you create great looking gradient fills for your text: Gradient fills look great as text fills only when your text is fairly large sized. Also, using too many colors in the gradient fill may make your text distracting. Try to use the gradient colors which contrast well with the slide background. Also use gradient colors that are not too different so that you achieve a subtle merge of colors.
Learn how to add a gradient fill to selected text in PowerPoint 2011 for Mac.

