This is so really hard to say special cause its difficult to explain specialty in short word
Some of them  are given below:

It’s a type of currency which know as peer to peer currency and this permit to send and receive money without help of broker or third party involvement 
Every bitcoin holder can review their account information after sending money or receiving money from their account.
After all kind of transection bitcoin recorded sufficient proof of every client and account holder through different facilities.
Buying and selling process is so much easier than other currency
I think above mention quotation is sufficient for proving that how much special the bitcoin is.