Keeton cutters are GREAT. They are all pretty old and can be finicky (need to keep them clean), but they are still well regarded by framers. I have one with a Hendrixson head on it and wouldn't sell it. They are perfect for DIY printers. The one you have pictured looks like it has all the goodies (square, stops, etc)...snap it up and don't think twice (and if you pass on it I call second dibs - seriously ). One thing to watch for is bad chrome. Apparently they must have made a large batch w/ chrome that flakes pretty easy.
I, too have heard that they are the be all end all of mat cutters. I haven't laid my hands on one and happen to love my die hard old aluminum Fletchers, but the only other ones I've used are the little 30" tabletop Logan (a good small cutter) and a professional C&H (had a chip board base...prone to warpage).
Like DAP said, KEEP IT CLEAN (cover it with a dust cover when not in use), and wipe it down periodically and it will give you many years of good service.
I just joined this forum today. I have one a Keeton Mat Cutter that I am restoring. It is very solid, but needs some work. I will post some images to this site once it has been completed. If you need direct contact, please email me at email@example.com