Well, I can tell you what I am *hoping* he brings to the table with my mare that is foal to him!
The first thing is type and frame. My mare is not a heavy mare at all (via matcho AA) but she could use some improvement in neck set/ shape, "typiness", and a tighter frame.
The next thing is leg conformation. According to the Hannoveraner Stallion Book he is improving conformation of both front and rear limbs.
Jumping ability/ athleticism. He of course did very well himself as a young 3-day horse and the Trakheners are a bit more versatile in the cross over of jumping and dressage. I am hoping he passes this on.
Temperament. He is generally considered to pass on good rideability.
What I am thinking he will not give is huge gaits and I am OK with this. Frankly, I am not a lover of the huge front end movement and much prefer a horse that has more swing through their ENTIRE body/ back. I think he will at least pass on three solid gaits, so not a loss but not a gain in that respect.
Lastly, and not the most important but a wish, a black keeper filly with all the above qualities I am really hoping for a replacement for my dam as she is getting older. I chose Buddenbrock for the above reasons but also as an addition to my program for future generations of breeding. I like that he is not the D,S,W,R lines as that opens up a lot more stallions in the future and I have wanted to add some Trak blood to my breeding program for a long time. But all of this is moot if I get a colt! That will be for sale