Gradients and drop-shadows require space to be effective. Pages also need white space to help organize content and avoid crowding. So, if you go with gradient

Gradients and drop-shadows require space to be effective. Pages also need white space to help organize content and avoid crowding. So, if you go with gradients or drop-shadows (or effects in that realm) know that you're doing so at the expensive of a resource that adds readability and overall usability. That's not an argument against using these things, just an argument against gratuitous application. (Consider that Amazon, for example, manages to get a good deal of content on their pages while still being fairly easy to grok.)