I have had mine since October 2009, replaced the blade once. There was a decent stretch in there where I didn't use it much but since like Dec of 2010 I have still used that second blade, with no problems.
The only problem I have had was if it is an old blade and week sticky on the carrier it can cause the blade to skip.
I love my Robby, I admit I have gotten lazy and don't like to hand cut anymore
. This was one of the best $100 I ever spent to pick it up. If you plan on doing a lot of Card Stock they aren't required but they make life REALLY easy.
My build projects have a work flow now.
Night 1 Print loads of paper.
Night 2 Turn on Robby and Cut, once you have all of a page type done Edge those while Robby cuts the next type.
Night 3 fold and Glue.
I have made some of my own GSD files for some Terrain features I made for my home game and they aren't hard to do.