My DD was slightly 'delayed' in words and clarity, but at 4 years is similar to her peers. Certainly would not have had 60 words by 2! (just looked up the blue book and it only asks for use of 5 -10 words at 18-21 months). My son seems to be following a similar pattern. Both kids showed understanding, just not the speech. DS not only signs and gestures, he does interpretative dance to tell his stories.

We did through speech therapy with DD, but i really think it was largely time and maturity (connection of synapses?) that led to her speech becoming clearer and more prevalent. Signing and giving her time to get her thoughts across helped deal with the frustration.