It seems to be good and they are very active. They also support tipping.

But I'm not sure if I like their 2-of-2 scheme. I would rather have a 2-of-3 one. Maybe I should re-read their paper.

Another thing that bothers me is that it's not very safe by default. The only way to be safe is if you use a (reviewed) plugin and you don't let it update automatically. Because if you use Javascript instead, they can take your key whenever they want. Imagine if the FBI seized their servers and injected Javascript malware like they did with Tormail.

disclaimer, I'm the founder of GreenAddress ;)

2of2 with time locked transactions means you can prevent double spend and thus allow instant confirmation.

the android app doesn't update by default and the chrome app doesn't update if installed from github but otherwise you are right although the web client remains useful for watch only mode (no keys) or for small amount

these two local and open source wallet clients also verify data before signing against the electrum network.

we are also working on our api, plugins for popular open source wallets (including hardware) and a full Java desktop client using bitcoinj.

we also worked hard to make all user transactions non correlatable to users or us (instant confirmation is out of band) and are working on a bunch of interesting things on top of it

> 2of2 with time locked transactions means you can prevent double spend and thus allow instant confirmation.

Could you explain this more, or link to an explanation?

Sure, I posted the design document/'white paper' here:

http://blog.greenaddress.it/2014/04/05/firstpost-updates/

Direct pdf link:

http://ghgreenaddress.files.wordpress.com/2014/04/greenaddre...

I've put a warning that suggests to users to use a local app!

That's great, thanks.