Writing Feedback / Expository essay on cell phone's impact. [3]

I need a little opinion of my essay...the topic was "The impact of cell phone use in everyday life." I also need help with a final conclusion...

In today's society, cell phones have become a major asset to people all over the world and more than 75% of the world's population owns a cell phone. Cell phones give a great contribution to how society communicates and save a whole lot of time that is wasted on communicating in person. Say someone wants to meet up with a friend, instead of sending a letter to them that will take days to deliver, all they have to do is send a quick text message or call them. It's a more reliable and easy way, and while it might cost more, it'll pay off later. The many applications that come with a cell phone are easy to use and a great assistance to staying on task, for instance, a clock and calendar for keeping track of the time and important dates, and a notepad to save thoughts or reminders.

Opinions? Revisions?