We have had a couple of Epson Stylus printers and both used these ink cartridges. Obviously both printers have different levels of printing quality but as we have also tried "compatible inks" from other brands, we have a good comparison.

The pack itself is about £30 on offer in most shops such as Wilko and this is the cheapest it can usually be found, online is no cheaper. In comparison, other inks we bought for our printers could cost half this. This makes these inks incredibly expensive. This is justified if the cartridges last a long time right? Well yes, but these don't last exceptionally long. If anything I would say that the lifespan of each of these is on par with the majority of them - they do not last longer nor do they last fro any shorter amount of time as other branded ones do.

They do have an advantage though. The ink is absolutely fantastic!
It has some technology known as Ink-Lock (or something like that, I can't remember exactly) which penetrated the paper better or something. What this technology actually appears to do is make the ink waterproof! This means that if you flick the odd bit of water over the paper, the ink will not run one bit. Yes, the paper will become soggy unless you have some revolutionary waterproof paper but the text is still readable. this is nor a privileged I enjoyed with the cheaper ink cartridges for the printers and it was a real hassle when I had to re-print sheets frequently - therefore actually increasing cost.
One main circumstance where this will be most useful is when printing photos on glossy paper as a small drop of water will not ruin your print and your cherished memories will remain intact on the sheet!

An annoying thing about these cartridges is that, because of some special Epson chip on them, they cannot be refilled as explained to me my CartridgeWorld. This means that you need to keep on buying the official inks which can get very expensive - it does mean however that you always enjoy perfect prints.