Except for the little matter of losing your money if you forget your password:
http://www.telegraph.co.uk/technology/news/11362827/The-625m-lost-forever-the-phenomenon-of-disappearing-Bitcoins.html
And remember the story of Mt. Gox losing people's money right on its own computers and then claiming that hackers had stolen it and then claiming that it had found some on an old disk-drive and then ...
The value of bitcoin only exists in human minds, of course, value of things is based on consensus. However, it's natural that humans value something that facilitates collaboration like a currency. If we add to this features like durability, divisibility, consistency, fungibility, portability and SCARCITY, then we have a SOUND MONEY. If we add to this a DECENTRALIZED, CRYPTOGRAPHICALLY secure and potentially ANONYMOUS payment system with EXTREMELY LOW transaction costs and INSTANT transaction propagation like Bitcoin, then we have a good reason to value it, especially when compared to the LEGACY and CORRUPT monetary system controlled by central banks with the help of their friends.....