Being that this is my first ink review. My review style and how I look at things might change. I am assuming, though, that with experience comes wisdom.
This isn't your normal red. It doesn't jump out on the page like the red ink of English term paper. It's much more subtle and reminiscent of red brick. It has a definite dusty feel to it. The color sits better I think for those who aren't fans of red inks. It has the slightest of orange hues which aid the subdued nature of the ink. I think,though, that Diamine misnamed the ink. When I think of a matador (considering I've never attended a bull fight) I think a deeper brighter red like that of my favorite boyhood car, the Ferrari.
What this ink brings that some other reds don't is some good shading. Reds are often saturated to capture that vibrant color. Matador can shade from smokey pink tones to the darker red brick tones as well. I noticed when taking pictures that when it pools from wet nibs it leaves the slightest of sheens.
The ink is a little bit on the dry side. The first time I used it; it was in a dry pen, the Stipula Speed. Talk about a nightmare. It lacks a great flow in dry pens especially when the ink level is nearing its end, but it shines in we pens like this Retro 51. It doesn't have the lubrication of an Iroshizuku, but it isn't so dry as to be unusable. If you don't want to worry about flow, this is not the ink for you.
The ink is a no hassle clean though. It doesn't clog. It leaves not stain, and, come to think of it, would look great in the Franklin-Christoph Model 02 Intrinsic.
In the Field
It leaves barely any bleedthrough on the Field Notes Cold Horizon, which I have found to be very unkind to fountain pens. It feathers very little on the Cold Horizon paper and make Stipula's Medium nib look as thin as Pelikan's fine is. The Speed was that super dry pen, so take the previous comments with that in mind.
You can see it looks great and rich in a medium italic nib on Leuchtturm1917 paper. It has a some ghosting, but it's slight and normal with that paper and just about any ink
Pens: Sheaffer Prelude Fine Nib, Retro 51 Tornado Medium Nib, Cleo Skribent Classic Broad Nib
Paper: Rhodia Dot Pad