Speed limiter: This is best activated by driving the maximum speed you want to be limited to, press the LIM button, then toggle the speed control (silver thing) to the SET+ position. That is now the speed to which you can drive before the car complains of you speeding.
Once you've done that, you can increase/decrease the limit in 5 mph increase by press and holding the speed control up/down. A quick toggle will adjust it 1 mph increments.
The CANCEL button will cancel it. RES (push in on silver thing) resumes its operation.
Adaptive speed limiting: Press the LIM button. If speed limiter is displayed, press the CANCEL button. Toggle the silver thing to the SET+ position, or press in on it (RES). This will activate the adaptive speed limiter.
You can use the RES to increase/decrease the rate of acceleration/deceleration has it accelerates/decelerates.
CANCEL will cancel it and RES/SET+ will resume it. Use the SET+/- to adjust the detected speed if needed.
Adaptive cruise control (if the car is so equipped): Without LIM lit up, activate by pressing the speed control to SET+. LIM will light up green. Use the buttons to the side of the silver thing to increase/decrease the gap allowed.
CANCEL will cancel it and RES will resume. SET+ will reactivate it too at whatever speed you're driving at the moment.
The brake pedal can also be used to cancel any of these.
As for speed sign recognition, it doesn't do too well in school speed zones since it has no idea if the speed applies at that time of day, or other conditions. Signs around here say "School speed zone during restricted hours." I've never found an official definition of "restricted hours." It also does recognize when the zone ends.
It has also mistaken an off ramp speed limit for the speed limit of the main highway. That could cause a catastrophic accident with someone close behind in a 70mph zone and it suddenly decides to do 45 (or less).
That's why I don't use adaptive speed control but I do use adaptive cruise control.
More information, including limits of capabilities, in the owner's manual and iGuide.