This service is currently only available in the web browser. It offers more than the usual sharing options (FB, TW, email, LinkedIn) and premium users can save content to Instapaper, Pocket, and Evernote. It will even let you share stories via a unique RSS feed.
In terms of filtering, SwarmIQ lets you choose whether to show the unread post count for each folder/feed. You can also choose whether to see only unread posts, and there's a checkbox for oldest/newest posts first.
There is a search function. but it's reserved for premium users (not unusual).
As you can see in the following screenshot, SwarmIQ has a clean and simply interface with the articles listed with either the newest or oldest ones first. Readers can chose to have the article list show only the title, a snippet, or the full post. The articles themselves open up in an embedded window and not a popup:
Update: As I come back to SwarmIQ in June 2014, I can see that the interface has changed significantly. SwarmIQ is a little more responsive than before and the bugs I identified before have been fixed.
But in spite of the improvements, it still has issues. For example, tweeting a link to a story sent the bare link unaccompanied by the title or source. The service also tended to get bogged down at various points as I tried to save content, share links, or switch folders.
I can't speak for you but I don't think I could use SwarmIQ for any length of time.
I have been using SwarmIQ for about an hour now. It initially got off to a rocky start, but the service did settle down and start showing all of the feeds and folders that I imported from my OPML file. The service is still running kinda slow, and it takes a while to refresh between switching folders or after you mark all feeds as read. SwarmIQ is just over 2 years old and I think we can see that in its relatively sturdiness. It's an adequate news reader in many ways, but I have still found several issues that have turned me off. This service is laggy, and there were a couple times that the list of folders/feeds disappeared from the left panel. There's also a problem with the scroll bar for that left panel; I can't see the bottom because it seems to have disappeared off the bottom of the screen. And then there's the fact that I can't limit the folders and feeds to only showing up if there is new content. Still, SwarmIQ might not suite me but it still performs better than the review posted on the PC Magazine website. They saw it as terrible; I merely think it is inadequate.