Are the Critical Shot perks in the Archery tree worth the investing in?

Not in my opinion. Regardless of whether or not I have the perk, if I'm playing the sneaky archer I either kill something with my first arrow, or I don't.
And when I don't the extra crit damage generally wouldn't have been enough to shift it one way or the other.

As an 'combat' archer who never sneaks, they're pretty usefull. They make me crit far more often, and it speeds up the rate at which you kill things by quite a bit.

Two very different answers,and two very correct answers.
It depends on your play style.

Do you prefer to be a stealth sniper type character or a get mobile in the face of your enemy type character.

For the get mobile archer at least one of those perks are neccessary to advance to the ranger perk.

For me..? Nope, I prefer getting a sure hit from a sneak, or just shooting it out. I dont like having to rely on a critical hit that may or may not come.

Angry Orc, & Alexander are both right.
Like I said, for my playstyle it isn't really necessary. Sneaky/sniper sorts don't generally need it, given how high their base damage'll often hit.
But yeah, if you're going for a soldier character. Heavy armor, & archery or something like that, it can be a great boon.