Are validation server controls better than javascript in any way ?

Question

Are validation server controls better than javascript in any way ? Do they restrict us as we are only able to use the functionality that is provided by them. Please help me on this. I read about validation server controls from http://jai-on-asp.blogspot.com/2009/12/validation-controls-in-aspnet.html

Ok Point taken that we should have both server and client side validations. But the by what way we decide that we use validation controls or just javascript. One point thats coming to my mind is that of compatibility with different browsers....and updation and maintainability of them.

After chatting with my friends at Microsoft i got the following good point. One issue that comes up is that if we use javascript in a .js file we can reuse it in the entire application, on the other hand if we use the validation controls and give them some particular settings and they are to be used in entire application then we have to again and again write those settings in each and every page ! ... still trying to find a perfect answer...