Really bad. Giving it charges just replaces one ammo with another. 3-4 bonus damage is less than that of a good arrow, so it actually deals less damage. The low durability of wooden weapons compared to metal means it will wear out much faster (durability being a second ammo) 

You could argue that you're saving weight, but if you enchanted your bow with Strength instead you could carry more arrows from the bonus than you'd have Charges from the bow (432 charges, i checked. 15str = 21-21lbs = 440'sh arrows)

After all that, its still taking up 1 of 5 enchant slots. The Ethereal is the only real end-game ranged weapon right now, it should feel like one (stardust isnt easy to find and wood weapons are harder to repair)

So i suggest the following.

Ethereal to increase the durability of the bow by 3x, putting it on par with fine crafted weapons and WORTH enchanting.

Ethereal adds 10% armor penetration. Magic already does 50% right? With ethereal its 60%.

+1 range (range runes could be cool by themselves)

Either no charges (lets face it, durability/food is the anti-afk) or regenerating charges. Or just more. We can SUMMON arrows with Druidry, so we wouldnt even need to go to town to refill.

 

I think this would put wooden ranged weapons on-par with the current high quality ruby platinum stuff, which is leagues above "Yew" quality.

 

Did i mention you cant even poison an ethereal bow? Pretty big drawback there too =\