If you use third-party Twitter apps like Seesmic or TweetDeck, you might start visiting Twitter.com more often. Today, in an announcement that came as a surprise to many, Twitter revealed a site revamp that changes the interface, introduces new features and promises to be "faster, easier and richer."What are the highlights and lowlights of the new Twitter? Here's a preview of what you can expect and our take on the top two missing features that users wanted.The New Twitter: Welcomed Updates1. Two-pane interface. Twitter is getting rid of its single-panel interface of streaming tweets and updating it with two panes, making the site more interactive and user-friendly.The left side will look familiar\u2014this is where your tweet stream will appear as well as your actions (@Mentions, retweets, lists, etc.). The right side of your stream will display a visibly larger reorganization of information, such as your followers, who you're following, favorite tweets, lists, trends and suggestions of who to follow.The new interface is clean and well organized. Lists and trends are easier to view (requiring less scrolling) than with the old Twitter.[Want more Twitter tips and tricks? Check out CIO.com's Twitter Bible.]2. Embedded media. If you clicked on a TwitPic link in the old Twitter, the link would send you to the external site. Clicking on a TwitPic link in the new Twitter, however, will display the photo on the right half of the page\u2014without leaving Twitter.com. You'll also see more information such as other tweets that have linked to that same image. Videos, too, will be embedded. If you click on a tweet containing a link to a YouTube video, the video will pay right on Twitter.com instead of redirecting you to YouTube. This eliminates the hassle of closing multiple browser tabs once you're done viewing. During the announcement, Twitter noted that it has "done deals with 16 media providers," some of which include YouTube, TwitPic, Etsy, Flickr and Ustream, but didn't address specifics of the deals.[Twitter Tips: 5 Proven Ways to Get Retweeted]3. Continuous scrolling. In the new Twitter, the "more" button at the bottom of the page used to load older tweets will be gone. Now, you'll be able to scroll through older tweets continuously, without having to manually load more. The New Twitter: What Is Still MissingGreater "List" features. Lists, which are essentially filters, were rolled out almost a year ago. While many users initially jumped on the list bandwagon, many lists have been abandoned and few are updated (not to mention it's nearly impossible to search for one on a particular topic). Threaded tweets. Tweets can be difficult to follow, especially if you're involved in a back-and-forth conversation with a handful of people. Twitter knows this and yet the threaded tweet function that many have wanted for a while (and some third-party apps have) still hasn't happened. They have included a primitive version of this in the new Twitter, but replies are limited to one (that is, if a reply has a reply, it won't be displayed).The new Twitter has been tested internally for a few months, Twitter Co-Founder Evan Williams says. The new features will be rolling out to a select number of people starting today, and will roll out to the public throughout the next several weeks. Twitter says that during the preview, you'll be able to switch back and forth between versions. Kristin Burnham covers Consumer Technology, SaaS, Social Networking and Web 2.0 for CIO.com. Follow Kristin on Twitter @kmburnham. Follow everything from CIO.com on Twitter @CIOonline. Email Kristin at email@example.com.