The Bow has a high rate of fire, medium damage(uncharged), and arrows are fairly uncommon, material and crafting wise. Skeletons drop them often, though.
To compensate, the rate of fire of the Musket would be very low, taking between 4-10 seconds between each round. Rounds and gunpowder would be very limited (assuming you haven't farmed farmed for a while). The damage could be fairly high. Maybe break a wood/glass block on impact...? Accurate until 20-30 blocks(?)
The Flintlock would have a low-medium damage and take 3-5 seconds to reload. It could be inaccurate at ranges beyond 22 or so blocks.
The Blunderbuss would take a second or two longer than the musket to load, but does very high damage and is inaccurate beyond a range of 14 blocks. It fires multiple rounds to compensate.
I wouldn't know how a cannon would work exactly.
The point is that Bows and Guns would both have their pros and cons. Maybe bows would be used more, but Muskets would be pretty fun to use. Seldomly used or not.
Edit: They probably would be loud as hell, too. Also, I changed the ranges a bit.