The utility is that it's a trust-less transfer of value between two parties. Essentially, it's like being able to send cash, anonymously if you chose, to someone else, without an intermediary, in a way that everyone can see and nobody can challenge the legitimacy of.

It seems to me a lot of it is tied up in speculative investment. But there are some vendors who accept it and some countries (eg: Japan) where it's more popular and widely accepted.