I found my rotatrim in a skip! Works fine after being cleaned up a bit. Absolutely criminal to throw this out a few months after its warranty expired.
I believe the blade is self sharpening somewhat (on the back stroke) so you don't need new blades nearly as often as other paper cutters. Could be wrong, though.
They're quite heavy if you go up to the large sizes (mine's nearly as tall as me, eek!) and annoyingly I don't think mine does very thick card but I think some of the varieties do. If you have the money, they're worth the investment.