http://store.steampowered.com/uiupdate/
All hail open betas!

Yesterday was kind of a cluster****, with steam servers being down and people losing their friends list and whatnot.
I believe this User Interface update was the cause!
Also, all that got fixed so it's cool

There's a list of all the updated things there, but I think the most important ones are:

1. New Interface, obviously
   
2. Uses Webkit, rather than IE
   
3. More socialness
   

Now, I've only been using this for an hour or two, but it does feel kind of sluggish. Additionally, there's a bunch of threads in the steam forums complaining about the larglienss of the steam window. But it does look nice, and feels more intuitive than the old one.

it looks stupid and i prefer the old ui. i hope they don't force the change. i mean why the hell can't i alt tab and view my friends list instead of using that stupid overlay?

its in beta, so of course it's not fully optimized.

at first i didn't like it that much, but it's growing on me.

Quote from Steyene

I think it is shit loads better then the old one. Although I have gone back to the old one as the webkit payment window kept crashing steam.

that must feel familiar huh

It seems pretty good, it isn't taking up as much memory as the old steam was as well.

Only bad thing is that some of my games just became uninstalled :/

Good:
Slick looking
Neat message sound (That I'll always have disabled)
In game browser is 100x better
In game overlay is pretty awesome (Yay, clock!)

Bad:
Gradients. Everywhere.
Buggy, cant accept voice chats...but can ignore them huheuhe
Font seems weird, like its anti-bold
No mini-games window (No big deal but w/e)
Weird change to the steam icon, like some Valve guy failed with making it shiny Or just wanted more GRADIENTS
Tools list doesnt have icons

Really some of the bad things are hardly bad at all but I thought I would mention them.

Yeah, there are WAY too much gradients.

You KNOW you're an oldie when you can recognize THIS



And remember when friends never worked.

i just started a voice chat with piggypup and it worked.