The Canon IXUS 100 IS offers ISO sensitivity settings from 100 to as high as 3200. That would give you enough room to adjust your picture quality especially in extreme low light conditions. There will be picture noises of course, but the Canon IXUS 100 IS tries to make this as less as possible.
For shooting modes, this digital snapper offers several automatic modes including the usual program, portrait, night snapshots, kids and pets, indoor, and sunset. Those shooting modes are enough to give you great quality photos without worrying to much about what settings to use.
When in use, you have three shooting options to choose - the Auto, Program and Video capture modes. In auto, all the camera's automatic features come into play including auto-focus, images stabilization, smile and red eye detection. The Program mode lets you choose various settings including ISO setting, White Balance, Metering, Color Setting and Shooting Burst (continuous or single shot).