I can assure you that no string theorist would be interested in working on string theory if it were somehow permanently beyond testability. That would no longer be doing science.

I'd say many features of string theory don't mesh with what we observe in everyday life.

I do feel strongly that string theory is our best hope for making progress at unifying gravity and quantum mechanics.

String theory envisions a multiverse in which our universe is one slice of bread in a big cosmic loaf. The other slices would be displaced from ours in some extra dimension of space.

One of the strangest features of string theory is that it requires more than the three spatial dimensions that we see directly in the world around us. That sounds like science fiction, but it is an indisputable outcome of the mathematics of string theory.

The full name of string theory is really superstring theory. The 'super' stands for this feature called supersymmetry, which, without getting into any details, predicts that for every known particle in the world, there should be a partner particle, the so-called supersymmetric partner.