Not by a long shot! Better cards accept data from a camera much faster and may transfer the data to a computer or photo processing station faster.

For DSLRs I buy only the higher speed Lexar Professional  and Sandisk memory cards. They allow the camera to take high speed sequence photos as fast as it can. At sporting events and shooting wildlife, high speed capture has saved me many times.

A friend of mine has a Nikon D300 (prosumer level DSLR). When he switched from cheap memory cards to the Lexar 300x cards, the length of time he could shoot continuously at the highest camera speed almost doubled!

In terms of the physical sizes and shapes of the cards, most full size DSLRs use a larger card called Compact Flash. Small DSLRs and most point and shoots use SDHC.

Cameras that use SDHC cards usually don't have a stressing high speed continuous capture mode, so slower, cheaper cards or the Eye-Fi card (to add geocoding), should be fine. There's nothing wrong with using a faster card, though.