Before going with a Strider I carried a Microtech Tarzuola automatic side opener.

http://www.888knivesrus.com/product/MTTERZUOLADA

Advantages? Definiately coolness factor. In some tight spots it was easier and faster to open it "automatic way" than traditional way. Side openers have stronger locks and you can also jab with them. Also this particular knife can be used as a manual knife. Automatic mechanism is deployed by bolster twists which is impossible to discover for a stranger to this blade. So in a place that is not friendly towards automatics you can operate incognito.

Problems with automatics? Accidental deployment while in your pockets.