John Cone's Piezography inks are the Maserati of B&W third-party inks for inkjet printers. I say Maserati because their proper use requires the sort of dedication and attention that a fine car like the Maserati requires.
These inks are a requirement for anyone who is serious about B&W digital fine art printing. But they are not for amateurs or the faint of heart. Use of these inks requires one to obtain, install and learn how to use a raster image processor ("RIP")program. Quad Tone RIP used to be the one Cone recommended. (It's cheap.) As with any new software installation, there is a learning curve for both the RIP and the inkset.
With these inks don't expect to just stick a sheet of paper in the printer and have a masterpiece emerge on your first try. You have to do your homework first. However, if you're willing to invest the time and effort required to learn how to use these inks, the expenditure will pay off in breathtaking black and white fine art prints.
On the other hand, if you're not a serious B&W printer then skip these inks, forget about the RIP and buy an Epson R2400 instead. You'll save money, the prints will probably be good enough to satisfy you and the learning curve is virtually non-existent.