I received samples of ink from Hieronymus Stationers Ltd. more than a month ago and I've been using Brown 02 fairly regularly since then in my Pelikan M605. My initial impressions of the inks that I received can be found here.
I generally am not a heavy user of grey inks because I find the colour to be too cold but Brown 02 is a warmer toned grey that has pleasant shading properties and is well behaved. While I have significant reservations about the ink's price, I have no complaints about its performance.
Shading: Yes, a nice shading ink that displays these properties even on cheaper papers.
Bleed Through: Copy Paper experiences bleed through.
Show Through: Show through on Copy Paper would likely be an issue for most users. Field Notes and Rhodia worked well with the ink.
Saturation: This is not a saturated ink.
Water Resistance: This ink is amazingly water resistant.
Drying Time: Average, 20 - 25 seconds using an EF nib on Rhodia.
Flow: No complains, the characteristics are in line with other good quality inks. No hard starts experienced.
Colour Make Up
As I mentioned above, I don't have a huge supply of grey inks and none of the ones that I own have the warm tone that Brown 02 has.
This is a good ink. If you are OK with the approximate US$48 per bottle then you will likely enjoy the writing experience but when Iroshizuku can be found on Amazon for $20 it is hard for me to recommend this one.
For other reviews of this ink search Ian Hedley's Pennaquod search engine.
Hieronymus Stationers Ltd. provided the ink that was reviewed above. I do not feel that my opinions of this ink have been affected by receiving the samples free of charge.