Essri doesn't offer huge variety of products. Basically you can get two inks: blue-black and black that contain iron-gall and are fully waterproof. There's long conversation about this ink under Sandy1's excellent and in-depth review of this ink and you should definitely read it.
To my big surprise it seems that ESSRI has a huge following, mainly because of the unpredictability of the resultant color when it dries. Depending on the pen - paper - nib combination you use writing can have nice shade of blue or look nearly black.
It's fully wateroproof and shouldn't fade with time even if you post it in the window.
Personally I can't understand all the hype about this ink. I've received 8 ml of Essri and tried it in few pens. The ink is dry and writing with it is unpleasant. It doesn't offere reasonable lubrication. The color is dull. My biggest criticism isn't the dryness though (although for me it's deal breaker) but the fact Essri tends to clog pens. I've tried it in four pens and with time it's clogged every one of them (between 2 - 7 days of not using the pen).
I say no to Essri. I believe at the moment you can easily buy well behaved inks with similar properties.
Drops of ink on kitchen towel
Tomoe River, FPR Dilhi, M
Leuchtturm 1917, Waterman Phileas, M
Kokuyo Campus, Kaweco Skyline, M