there is no ETA. lightning developers have taken the position that there is "no rush" considering how much value is expected to be stored in payment channels. they are very concerned about ensuring that no funds are lost as a result of using the LN protocol.
having said that, it's pretty widely expected that LN will be usable by the general public sometime this year, likely in a matter of months. the next major step is to complete wallet implementations. we're already seeing lightning transactions on the network; now it's mainly just a matter of releasing the software.
It's not like there's an actual "official LN launch" date or anything like that. Rather LN will be "launched" when people feel confident enough in one or more implementations of LN to use it on the main Bitcoin network. In fact, you could consider LN to already be launched as there already are people using LN on the mainnet. Of course those people do so at the risk of their money, but nonetheless, the software mostly works and there are transactions occurring.
I wonder how a Lightning user interface would look like. Instead a "Send" button there will be "Open channel" button (same fee as just Send button + X bitcoins to deposit into channel) and then "Send via the opened channel" (no fee) and then "Close channel" (same fee as just Send button). Given this complexity and the fact that you have to spend twice as much in fees to send same amount of money as without LN I really wonder how the "greed" would work.
It's very likely that it will still just be a "Send" button. Channel management and all that will actually be handled by the software automatically. You put money into your LN wallet, and it will use that to open and close channels automatically. So when you want to send Bitcoin to someone, your LN wallet will have established several channels. It will also determine an optimal route and do everything automatically for you. There's no need for you to manually open and close channels yourself; the software will handle all of that for you.