This is so really hard to say special cause its difficult to explain specialty in short word
Some of them are given below:
Its 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.
The special thing about bitcoin and other cryptocurrencies is they can pump more than what we expect and also fall down. While the currencies we know just move a little from time to time and most of them were handled by the government.
Bitcoin is not handled by the government and I think that is the special feature bitcoin have than other currencies. Second is how bitcoin grows in the market so fast that no other coin do the same so many people are getting interested to try their luck by investing to it. Maybe if bitcoin continue to grow and add more features on it there's no way any other coin could beat it in the next more years.