Compared with the original cartridges of Canon these cartridges are really very inexpensive (20 cartridges for 20 Euro). With the print quality, I am satisfied. However, I print mostly text and simple graphics. (I did not have experience with photos.) So far, all cartridges have in my Canon Pixma iP4950 is working properly and the level is displayed by the printer (driver).
With the removed protective cap must be slightly careful, because usually it is a little ink. (Maybe that's when the original cartridges even so, I do not know.)