Vanity TLDs have failed every time. I can't imagine .eco will take off any more than .jobs, .info, .travel, or the myriad of others.
The worst one was .museum. Just a way to shake down big companies like Coca-Cola who now have to go buy coke.eco, cocacola.eco, drinkcoke.eco...
.info are particularly popular with kids wanting their first domain - because they're normally v. cheap. Probably not what was had in mind for them, but they're definitely more popular than many realise.