With regards to your GUI question... that is the whole point of a web wallet, there *is* no installation. No counterpartyd to set up and install. You simply go to a webpage, generate a passphrase, paste it into a text box, and click login. Takes all of 5 seconds. Nothing to save or worry about beyond your pass phrase (which *is* your wallet)
This kinda reminds me of NXT - any chance we run into same security problems with that, as they did?
Just need to have the (brain)wallet refuse or complain a LOT about low entropy passwords
Whoa back up now. You guys are going to implement the online wallet as a brain wallet???
This is incredibly insecure.
What is wrong with generating random public address / private key pairs like all other online wallets?
Isnt blockchain.info essentially a brain wallet anyway, since all you need to generate the key is the original passphrase?
Personally I like the brain wallet idea, but why not just implement James' suggestion and refuse any passwords that are shorter than, say, 30 characters? And have a big warning about choosing a secure password.
Could also consider adding an optional two factor login with Google authenticator or something similar.