Many of my clients start our conversation with a request for a "super slick" presentation. I think "slick" is not the most important requirement of a business presentation. I usually go for a restrained, professional look. Here is why too much slickness might backfire:

• Nobody trusts a smooth talking politician or car salesman. Super slick graphics might just give the impression that there is something to hide.
• Spectacular moving visual effects might just make the audience giggle, because it sort seems out of place for the setting of a small conference room presentation
• Complex graphics create technical and practical problems. They take a lot of space making it harder to share documents, videos often go wrong in live presentations, breaking the flow/momentum of a pitch, custom-made graphics are hard to edit and change (presentations are living creations that change all the time), fonts always create problems when they are not installed properly
• "The cliff": often I see incredibly sophisticated presentation starts (slide, 1, 2, 3), but pages 4 to 50 look incredibly boring with standard bullet point slides.
• Often the key to a pitch is not a dramatic trend, but a small, clever innovation that makes you stand out. Investing a lot of time (and money) in visualising a mega trend that is already pretty obvious to everyone ("facebook is big" for example) is a waste of effort and takes the attention away from the really important point in your presentation

"Slick" does not always help to make your message clear.

Image taken from WikiPedia