Have not used the slip covers yet but I did try one on a dining room chair -- I loved the new look!  I am having guests for a friend's BD   -- so I think this is a great way to protect my dining room chairs from everything (if you get what I mean)
And an excellent way to change the look.  The covers donot fit as nicely as I would like so make sure you check measurements if you plan to use everyday.  I love this site .. so glad I found it.  Also price point was good for me.