!WARNING! Scary wall of text ahead.
Oscar Mike. Not going to lie, when I first came in I thought he was there just to appeal people who played games like CoD. Not that there’s anything wrong with that, just saying that game is pretty straight forward.
After using him to unlock Benedict and work on getting Galilea, I am absolutely stupefied at the amount of damage he can do. All you need to know is Napalm with the 50% wider AoE, and everything that increases damage or shield penetration.
I’ve found that the best way to ‘use’ him is simply do this (there may be better, but this takes absolutely no real ‘skill’). On your gear, put an item that gives you +Damage% (mine is a white so I can get it nearly at the start of the game), +Shield Penetration% (again, mines white). The last item you can either do something for attack speed or reload.
In-game, the upgrades you need off the top of my head is grenades explode on impact, napalm, red dot, +15 tactical rounds, cloaking starts shield recharge, +50% Grenade AoE, the +3 slow on Ult, and all the things that increase damage.
The amount of damage you will output is insane, the napalm is good for locking off a narrow way to somewhere or dealing a lot of damage to an enemy/minion group, and all you need to do this is those skills and gear.
Let me explain why he is OP, besides just the damage output. So obviously he has insane damage from this. If you get an assist, 95% of the time you will be the Top Damage Dealer. But aside from that, he can use the grenade to clear out a group of minions, making a pretty good pusher. You can use the same grenade to good damage quick to an enemy, and also deal DoT in that area. You can also use the grande to shoot behind cover enough to where the enemy has to move out or take the DoT. The grenade is very versatile. For the cloaking, you can et out of nearly every situation, and even just use it to regen your shields quicker. You can reposition, escape, recharge, all of that. All you have to do is when you are invisible jump a couple times to break sight and reposition and take them out. His ult is absolutely amazing for using on a group of Battleborn or Battleborn and minion and clear them very quickly. It’s just amazing in and of itself. But the main thing is his damage. EVERYTHING falls so quickly to him, even Montana as long as you hit a good amount of crits.
On to the gear. His already amazing damage is boosted still with a gear that boosts damage. Enough said. If you pick reload speed, you can reload quicker and continue to spit out damage, boosting your DPS. The same goes for the Attack Speed boost, obviously boosting your DPS. But the small amount of Sheild Penetration from the gear is insanely useful. Since to get the maximum damage, you won’t be using any shield penetration from the upgrades. But this gear having a small amount is just enough, and works very well. It doesn’t happen every two seconds, but sometimes you get a kill just because of the shield penetration. Mostly, is just good for putting a bit of ‘permanent’ damage on the target that they need to heal to get back.
All this equals Oscar Mike, the Point and Shoot master. He is OP, atleast in my opinion. What I think it might be is just that fact he is so simple to play. Since this is more or less a new type of game, a lot of character might take some learning. Oscar Mike is extremely straight forward, so maybe it’s just because of that that he is so good.
If your looking for stats, I only have 6 deaths with him, a little over 80 player kills, one loss, and (doesn’t show on stats) average about 60-70 minion kills a game.
TL;DR: Oscar Mike is OP. Now go back a read the wall, lazy bastard. 
Also forgot to add, sometimes is dialogue is kind of funny, but walking from point A to B and hearing the same thing three times is extremely annoying.