Just a couple things. For level 20 did you mean +10d2?

The saves seem good, as do the skills (as nonspecific as they are, its still obvious what you mean), BAB is good.

The only thing I'd have to say is that the multishot seems slightly overpowered. By 20th level, thats a possible 20 arrows in one round, even if it is only 3 times per encounter.

Threatening a critical hit is also extremely powerful, but maybe not overpowered. It's a very nice class feature.

Perfect shot works well because it's at such a high level. (What class isn't complete without some death-causing attack after all?)