This gives the continuity of the work or tasks the users are working on. Instead of trying to repeat exactly what you have done on your iPhone or iPad, you could now continue where you left off on the Mac.
Not something super fancy, but it is cool.
What do you think?
The down side, since it is still on Beta 4, it may not work all the time.
I noticed only the Mail app works well in Handoff, the text messages, some how kind of slow.