From what I've read in the past it is a necessity. I'm ordering mine next month and plan on getting it.
I love the blade cleaner. You don't have to have it. Because you still have to wash the blade. But the blade cleaner helps get all of the cake crumbs off of the blade, even when they have dried on there. I wouldn't want to be without it! I think it makes the cleaning process safer to be honest with you. Because it does the hard work, and then I just run a warm soapy washcloth over it and then one to rinse it off and then one to dry it with.
Definitely get the blade cleaner. If you're leveling/torting several cakes, you'll need it to clean crumbs off between cuts.
I also use it as a nifty little rolling pin when I have to do something quick and small. It is kept in a drawer under my work surface.