It's more than imperfect it's practically useless in its current state. It provides exactly 0 proof of identity or trust. It's basically "oh, you're advertising an SSID with <name>? I'll connect to you and we can make up a trust after that".
0: https://emaknyus.blogspot.com/2011/07/airpwn-bringing-goatse... (warning, likely contains goatse - image did not load for me)
People act like there is 0 harm in prematurely releasing a security feature in a network standard not remembering the various network hardware that will be made based on this don't follow a software development lifecycle where you just publish sprint 2 a few weeks from now with improvements and the world moves on. Even when things get updated wireless clients that are easily updatable (e.g. iOS/Windows devices) are only just recently using TLS 1.2 in their PEAP sessions. We shouldn't be playing fast and lose with security implementation in a future standard just because it sounds nice at first glance and assume sounds nice is better than nothing. What if we decide the next iteration of this design is to rely on PKI to create a chain of trust and now we've created 5 years of shit not working because wireless implementations are so shotty? Similar things have happened with other wireless standard revisions already... hell 802.11ac spent a lot of time and planning on MIMO (which is well established in other radio specifications already) and we still got an entire generation of wireless hardware that worked better without it enabled due to lack of real world vetting.
The best hope in this case is everyone realizes this doesn't provide any meaningful security in the current revision even though it's already available and being pranced around as a great security benefit.
/Rant of a network standards guy
But—correct me if I'm wrong—it does help in the case where you have a home wifi network, that your devices all connect to, and remember the network. It will encrypt all the traffic of your devices. An attacker can't create a different network with the same SSID and trick existing devices to connect to it, right?
If I'm right, then this is quite valuable. It means that most home users can have an encrypted LAN without having to remember the password and tell all their guests what it is whenever they have a visitor.
Can't he? Wouldn't the existing devices just try to connect to whatever broadcasts that SSID.