Originally Posted by rochow ...You can argue all day about how its quicker, easier or whatever - but you CAN'T argue that its "lightweight" in comparison to coding your own.

Oh for sure. Especially if you just need a couple effects here and there.

However, there is a trade-off between a few kb per page-load and the cost of the time it takes to write that code yourself. If you just need a couple functions, sure, just go grab or write scripts to do those specific things. But if you have a larger project that's going to use a good portion of a framework's functionality, I think it's worth it. The time saved writing AJAX calls alone can be substantial, and if you add animation into the mix, things really begin to add up.