They ARE big, and they ARE powerful. The Dutch Warmbloods have a strong farm horse (Gelderlander) background, so compared to the Swedish Warmbloods they are more harness-horse looking - although that's being bred out as the eventing horses are picking up the big money now.
The warmbloods as a whole don't seem to be as flighty as the Thoroughbreds, although you can always pick two horses out that prove the rule. One of my trainer's Trakehners is just evil-tempered (we blame it on her sire, the Olympic competitor Abdullah who was a notorious bad boy) and she also will get away from you competing or hunting, while my T'bred mare is incredibly tractable and reliable at all times and places. T'breds are also renowned for never giving up no matter what. If you pointed my mare at the barn she would try to scramble over it. (Maybe that means she's stupid, but you have to exercise judgment when riding a T'bred because she will go until she drops in her tracks.) Mine won't get there in a hurry, though, she's beautiful but she was sold off a racehorse farm as a yearling because it was already apparent that she couldn't catch cold.