Along with the above SD card, the camera is very fast, looking at the pictures on my Canon IXUS 500 I always have to wait 2 seconds to the next picture when browsing (despite very high quality CF memory cards from Lexar and Sandisk - that was but then at the digicam and not on the memory card), in the 900 does it with this card Rip-Rip without waiting. Also the snapping of pictures is quite fast forward - all without having to wait.
For snapshots, this duo (IXUS 900 Ti and SD Extreme III) is just recommended!
Have had almost a dozen memory cards from SanDisk and several years in continuous operation, and not a single failure. The quality is generally excellent, and this card especially well.
My tip: Buy, would and will still grow me of this memory card.