Between the twisted mouth and the middle section being at an angle to the wire sections, it is probably pretty harsh. We used a twisted wire snaffle breifly on my 5 year old's half-Gypsy pony, because he knew he was big enough to take the reins from her and run off with her, or stop to graze, etc. It was a good solution as a temporary retraining method. I would not want to use a bit like that all the time, personally.
Depends a lot on the thickness of the bit itself. Thicker is less harsh than thin and the more it twists is more harsh than less twist.
The D ring does not allow the bit to slide giving you more "talk" to the sides of the mouth/lips if you want to take more nose.
The stop is against the bars and the tongue introducing slight pressure on the poll. Not a bit w/ a lot of whoa but enough.
The "dogbone" allows the bit to break putting less tongue pressure than a regular snaffle and allows you to put pressure on one bar or the other if one rein is used.
When you use both reins, you talk to both bars and the poll indicating whoa.
Nice bit for specific moves, good step up from an "O" ring snaffle. Introduces different pressure and reaction laying the foundation for the next step of introducing short shanks or a different mouthpiece.