One thing missing is support for the RAW image format.
There are some ultra zooms that support it, but the S5 isn't one of them.

Main features: 

• Save images in RAW format 
• Ability to run "Scripts" to automate the camera 
• Live histogram (RGB, blended, luminance and for each RGB channel) 
• Zebra mode (blinking highlights and shadows to show over/under exposed areas) 
• An "always on" full range Battery indicator 
• Ability to turn off automatic dark-frame subtraction 
• a higher compression movie mode, and double the maximum video file size 
• exposure times as long as 65 seconds 
• exposure times as little as 1/10,000 of a second 
• ability to use the USB port for a remote trigger input

Additional features: 

• a depth-of-field (DOF)-calculator 
• File browser 
• Text reader 
• Calendar 
• Some fun tools and games 

http://chdk.wikia.com/wiki/CHDK_in_Brief