I gave TypeScript a try but honestly thought it was more trouble than it's worth in most javascript applications/libraries. Maybe that's just the lazy person inside me, or maybe my projects aren't big enough to make use of it's features.
Well, you don't have to write any declarations -- everything will just be typed as `any`, which isn't preferable but is exactly what you'd get if you weren't using typescript.
Eh, I guess it was mainly the learning curve and lack of payoff. As mentioned here, I think my project size wasn't big enough for it to show it's usefulness.