This is one of the most well-behaved and easy to maintain inks I've tried. I currently only have cartridges, but will buy a bottle very soon so as to use it in even more pens. It's extremely easy to clean out of pens and washes off my fingers easily.
My favorite quality of this ink is the color. It's a medium to dark blue, very similar to what I think of as "royal" blue. It's nice and saturated, which is something I long for in inks. It has good lubrication and excellent flow in the handful of pens I've used so far.
On nice paper, this ink does not feather or show through the page. Sure, it does feather on cheap paper, but what ink doesn't?
The shading properties are fantastic. Again, I see a stub nib in my near future just so I can play with this beautiful ink some more.
Overall, this is one of my favorite inks and I can't wait to introduce it to more of my pens. Aside from my quibble with the drying time, it's close to a perfect ink for me. I'd like to hear from you if you have some information about the drying time or have advice on performing ink drying tests. Next time you're looking for a nice blue ink to try, grab some Éclat de Saphir.