It counts your steps by using the sensors in the phone. Displays your pace, approx. distance, speed and calories burned.

It calculates the pace (steps per minute), and can help you maintain a desired pace by speaking to you.

It has an option to notify you by voice in given intervals about any value.
You can set a desired pace/speed and get notified when you have to go faster or slower.
If not accurate, try adjusting the sensitivity setting. Works best when attached firmly to your body.
On some phones it can't count the steps when the screen is off, try tweaking the "Operational level" setting if this happens.
Not suitable for all day use, as it consumes power constantly.