I already reviewed 802-40 soft
here, so I won't repeat things unnecessarily. Mostly I will compare this rubber to the 802-40 soft sponge version.
The red rubber and the black rubber have different sponges. The sponges are different colors, and they have a slightly different feeling.
The red rubber's sponge responds very well to boosting with Falco Tempo Long -- increased speed, spin, and feeling -- whereas the black sheet seems to not respond at all. I'll try again with Haifu Seamoon and post an update. I did not boost the soft 35 degree version of this rubber for comparison, because the sponge would probably become too soft.
The 42 degree version of this rubber can create significantly more spin than the 35 or 38 degree version, but control over the spin is very limited. The place where the spin capability really shines is in the serve, and more generally with short sharp strokes. When serving with this rubber you can make almost as much spin as with inverted rubber -- but you have to serve fast and long. The rubber will only create spin if you add power. As far as I can tell, it is not possible to create a slow spinny ball. With the soft sponge, there are more options to play slow spinny balls.
Touching softly will not engage the sponge, and so it will produce a dead ball (or even an antispin effect). This can be good tactically because it confuses your opponent. Essentially, the rules with this rubber are:
1. hit strongly and sharply to create your own spin (inverted rubber effect)
2. hit with medium strength from the forearm and wrist when flat hitting (classic short pips tactic)
3. hit very softly when giving your opponent's spin back to them (long pips / antispin effect)
Because of the hard sponge, this rubber behaves more like pips-out and less like inverted. It's easier to give knuckleballs and dead no-spin balls compared to the soft sponge version. Engaging the sponge creates spin. The soft sponge always engages, whereas the hard sponge only engages with strong hits.
802-40 soft is sensitive to incoming spin, so it is hard to return high-quality loops from the opponent. 802-40 Mystery III is significantly harder, and so is less sensitive to incoming spin. Blocking loops with this rubber is a lot easier than with the soft version, and usually you can just smack them back for a high-quality counterattack.
However, this harder rubber is less controllable than the soft version in general. It is very bouncy, and without the grippiness of inverted rubber, you have to be very careful about the angle at which you are hitting the ball. This rubber has a weakness with slow balls and is more suited to aggressive attacking, compared to the soft version.