There are things that RockMelt does that no one has built Google Chrome extensions to do (yet), though that seems possible since RockMelt is built on top of Chrome's open source code.

RockMelt supports all the Google Chrome extensions, though it could support many of them better. It's fast and clean and nice like Chrome - if you don't like RockMelt you should just use Chrome.

Here's what's unique about RockMelt.

The Good News

• The left sidebar Facebook interface is useful

  Switch the toggle on the top of RockMelt's left sidebar and you can display your highest priority Facebook contacts there. Yesterday the company added a blue highlight around the avatar of any of those friends who have recently posted new content to Facebook.
  

  
  That's a great way to keep close tabs on anyone you want to develop a deeper relationship with or make sure you don't miss any updates from. I've highlighted a couple of hip cats with good taste, some bleeding edge engineers that rarely come out in public for air but whom I'd like to get to know better and a few family members and old friends I'm most interested in or concerned about.

  That's a good interface for my highest-priority sources of Facebook updates, though I'm friends with more than a thousand people. Now I know I won't miss my wife's updates.
  

• Search inside the streams of Facebook friends

  Pop out anyone's recent shared items and updates from Facebook and RockMelt has a very nice search interface to limit what's shown. What was that link my friend Alex shared on Facebook last week? RockMelt makes it easy to find out.



• Easy posting and sharing to Twitter and Facebook

  There are lots of ways to post status updates and share links on Twitter and Facebook, but RockMelt's integrated sharing buttons are the nicest I've seen so far.



• Right sidebar support for lists

  Facebook lists are a great way to see key contacts in context. I've got lists for personal friends, key geeks that might prove valuable in my work and old school friends. It's good to be able to change channels between those streams, and RockMelt does an ok job of facilitating that.

  If you view your Facebook stream by a list, then choose "Tear off window" - that list will remain accessible with a click of the Facebook icon. The sidebar should remember your state though. It should also let you put multiple icons in the sidebar for multiple lists, and show a badge number when my personal friends list, or key geeks list, has an update to check. That would make list support much more useful. Support for the new Groups is a whole other matter, but ought to be there.

The Bad News

• RSS badges in the right bar update funky

  I've got some medium-priority feeds that I'd love to have updated in my right sidebar of RockMelt, but the pipes seem a little confused. I don't trust it.



• Social badges get overwhelmed and unresponsive

  RockMelt intends to put easy interfaces for your full Facebook and Twitter feeds in your sidebar. Maybe they work well if you've got less than the thousands of people I'm following, but for me the display is slow, unresponsive and choked up.



• Extensions that need toolbar space get no love

  RockMelt supports Chrome extensions and some work well. Apture works great, but anything that needs toolbar space ends up in the right sidebar and the fly-out windows turn flashy and messed up. Delicious and YoLink are the two I'm struggling with. I'd give up some adress bar space to get toolbar space for a few extensions. This might be the deal breaker for me, and the fact that the feed displays don't work reliably.

The Meh

• Pre-loading of search results in the background is a good idea, Google started doing it yesterday with its search previews feature and the same strategy makes Flipboard's UX all the more dreamy - but it's not that big a deal in RockMelt. And all the pages now sound an error audio notification for me when I click them. Chrome's unified search and adress bar is better anyway.

  Of all the things RockMelt could pre-load in the background, search results are of least interest to me. How about the updates from my high-priority Facebook friends, so I don't have to wait for those to load? How about my streams in my right sidebar? That would make a much bigger difference in my user experience that pre-loading search results does.

The verdict? I'm keeping RockMelt as my primary browser for now. Why? Because it's just Chrome with a Facebook sidebar and a team full of steam to fix the problems people have with the browser at launch. In the mean time, I use half-baked, broken software for a living - I can put up with its shortcomings.

If and when all the promised features work well, it's going to be a great way to browse with high-priority social contacts close at hand. So far though, it's probably too funky for very many other people to work with.