The ink is impossibly inexpensive. I have done personal side-by-side comparisons and have a hard time telling the difference between this and OEM ink. Sometimes the cartridges don't last as long as I think they should, but I don't really pay attention to my printing habits very much. In the end though, I just always keep at least 1 on my shelf and couldn't be happier.
I was apprehensive to try these, but at a fraction of the price that the BigOfficeStores are selling at, I took a chance. I bought and replaced the Cyan, Magenta, and Yellow all at once (but *not* the Black, that's still the one that came with the printer). It's been a few weeks now, and everything seems to be working fine. When the black gets low, I'll get that one from Monoprice, too.
PROS: Seems to work well with my Brother MFC-J825DW. Excellent price.