The first time I was assigned a draft horse to ride at my barn, when I saw her my first thought was, "Oh gosh she could kill me just by stepping on me!" (She was only 16.2hh)
As you can probably guess, she is the sweetest thing on four legs. She can take little kids whose legs barely reach past the saddle flap or do advanced jumping lessons. She is now (with the patience of a saint) teaching me how to jump.
Now, I work with a 17.2hh Shire horse who is also a gentle giant, and I have no fear of his giantness whatsoever, because I know with the big size comes an even bigger heart!