[nowprovision]

The Ethereum situation is very sad, a great idea flawed by centralization of power (or influence if you want to be pedantic in terms), and whilst you could argue technically all the miners control the network and anyone can participate if you look at recent events it is currently clearly dictated by Vitalik Buterin, slock.it and a few other heavily invested and conflicted* individuals.

When the DAO hack hit the fan Vitalik Buterin immediately instructed the exchanges to stop (and they did) and then started talking and planning for the hard forking within hours, this was not only a PR disaster (as it turns out it wasn't needed) but gave a clear signal to any spectators about where the power was centralized. He later tried to justify the decentralized nature by saying "see I had to beg the exchanges" https://twitter.com/VitalikButerin/status/743972769717641216 but history shows a far different sequence of events than beg and hope they listen. Smart contracts have a bright future, just not the ethereum implementation/network/fiasco.

*e.g. http://pastebin.com/aMKwQcHR#L45 The ethereum foundation can reimburse exchange losses. Without a hard fork and rollback this damage will be permanent and the ecosystem will die.