The only thing I dislike about DarkWallet is its name.  It is a sensible and important tool to enhance the privacy of bitcoin transactions. 

Imagine that you were a celebrity using bitcoin: every time you buy a coffee, TMZ is going to post the transaction if it gets the scoop!  Your obsessed fans would be trying to track your coins through the blockchain to identify where and when you are likely to eat dinner, shop, vacation, etc.  Coinjoin is a technique that would make it more difficult to be stalked by crazy people.  Privacy is important for our peace-of-mind and for our personal safety.