In my opinion, bitcoin has value because of many reasons:
First, the good ones:

• The security system that was developed for the bitcoin, the blockchain. A completely revolucionary  techonology that has written a new chapter of the Internet history
• Anonymous money transactions (But It might be a double-edged sword, though)

• A huge amount of people who believe in this technology and want to use it. It got very trendy last year!

But, there's also bad ones: 

• Bitcoin turned out to be the black market coin. So the huge amounts of money invested by criminals in this criptocurrency, makes the value rise.

• The speculation of the people who saw in bitcoin, a way for get rich overnight. 

Despite the Bitcoin Revolution, I don't think it as a functional currency in the long term. But I do think Bitcoin gave the world a great and powerfull gift that changed everything, and criptocurrency are here to stay forever, but it still needs some improvements before becoming and efficent way for economy exchanges.