Yes, I've been using this feature for the past few months now and it works great.
What happens for me is that all of the promotional emails that I get sent from web sites (Amazon, eBuyer, etc.) that aren't strictly spam get sent to the clutter box, so my inbox is free for more important emails. I still get some non-important emails in my inbox, but they don't swamp things as much as before.
The clutter folder is pretty easy to manage and you can quickly scan/delete the emails without worrying about skipping something you don't want to delete.
The downside is that the clutter feature can only be administered in the web Outlook interface or the full "Office" version of Outlook. Items can't be marked as Clutter on WP8.1 or Windows 10 Outlook (Desktop or mobile).