After registration, it will redirect you to Multiplx dashboard from where you can follow different topics that are already in their list. If you want, you can add any website you want to the list of websites. To add any website to MultiPlx, click on +Plx and specify the name of the website you want to add to your RSS feeds. The service also supports bookmarklet feature which can be used to add any website to RSS feed with a single click.
Most importantly, it allows users to easily backup their RSS feeds from Google Reader in few simple clicks. All you need to do is browse the location of the subscriptions file and it will automatically import all the RSS feeds. The time it takes to import the feeds depends on the number of websites you are subscribed to.
You can even create a backup of all your RSS feed by going to your account settings. It even allows users to export all the websites they starred, liked and shared as well. It also offers users with wide range of options to customize the look and feel of Multiplx such as change view style, feed list location, favicons and much more. The service is still in beta stages so there is a high probability that you will come across errors. But the service looks promising and may be one of the best available alternatives. Check out MultiPlx