Bow is interesting. Before ravager nerf, I would have wholeheartedly recommended it right along with gunslinger. But now that rage hits don't proc zeal, blessing is a bit underwhelming. So now it's not as clearly a good sub choice.
Bow basically has 3 things: Blessing, speed buff, and corrosive shot (for -def). Blessing is decent, but like I said, it's not as good as it used to be. Combine that with the fact that you can only get it to 90 second cooldown with cap speed and it's really not all that impressive. The speed buff is good, but gunslinger buff gives about 1.5 times as much so if you build around your speed buff you may as well go gunslinger. Corrosive is similar to slash cut but not nearly as strong unless you get several stacks up... and by then the boss is almost dead anyway.
Overall, bow sub kind of falls short when compared to gunslinger or duelist. It's pretty much just a worse gunslinger because it has lower speed buff and ice trap does more damage than blessing + corrosive, and can be used on every boss without interrupting rotation.
The one reason I could see to use bow sub is if you very frequently party with a gunslinger. If that is the case, both your own speed buff and ice trap would be wasted, so there's not much point. But in that case I would probably run duelist sub instead, so tbh I really don't see a point to recommend bow sub. But I made a section for it anyway just to explain why.