Flash enables a web designer to create interactive content with minimal development knowledge. However you need to remember that various flash elements consume time for loading the page. 

As time passes by, Macromedia Flash or Adobe Flash today had transformed rapidly where you can manipulate vector, raster graphics and support bi-directional streaming of audio and video. 

This technology when used or applied properly in your web design Leeds process can absolutely help you to overdrive with what you are expecting. However, it can also cause site degradation or it can lessen the effectiveness of your web site as a whole.