Timid puppy.... good or bad?

I am considering taking one of my friend's puppies - however, the only one left (a female) is also the smallest and most timid of the litter. She is fine when handled - she shivers, but they all do at this stage (five weeks old). However she doesn't make noises or lick me, unlike her brothers and sisters, and is extremely reluctant to come out of her kennel into the pen, again, unlike the other pups. I have no problems with her being small, or with her being quiet. However I have heard some things about timid dogs that are putting me off a little eg that they are so anxious when left alone they tend to be more destructive than other dogs, and that fear of other dogs & humans can turn into aggression as they mature. Does anyone have any experience of timid dogs, good or bad? Has anyone chosen the most timid puppy, or the 'runt', and if so how did it turn out? thank you!