Better known as 'Gearbox does Monday Night Combat'.
It's not terrible, depending on what you wanted. Got my hands on it tonight for the first time, and my early impression is that ranged characters are terrible. Hitboxes are small enough, the damage is too little, the halo shields regen too quickly and move speeds are high enough that you have to be better than a Tribes sniper to do anything noteworthy with a ranged class, with rare exceptions. This is far less true for the PvE mode because none of the AI is currently designed to rush you down in melee and most of them are far squishier than player opponents.
The PvP is 5v5 two lanes. Each team has a minion entrance and a goal in those lanes, essentially a big death furnace for your little robot friends to lemming themselves into. The first team to get 500 of their little payload carts into the goals wins. You can spend a minor amount of currency to upgrade your character with pre-selected equipment earned in PvE, but most of your money will be poured into map nodes. There are spawn locations along the lanes for health restoring stations and various kinds of turrets, and either team can hit 'R' when on a node to pay a small fee to activate it, when it will remain active until the other team shoots (more likely stabs) it down. Because the game lacks typical MOBA turrets at the start and forces players to spend money to help the TEAM instead of THEMSELVES, expect nothing to be built for the first ten to fifteen minutes of a match because each of your teammates will be trying to max themselves out before anything else.
The PvE felt a lot like Borderlands without the inbetween. The one mission available right now seems to take about ten to twenty minutes depending on how much the players know what they're doing and if they've done it already. It consists of running through a gauntlet of enemies, fighting a boss, then another gauntlet, touching an objective mcguffin, and another three stage giant spider named Geoff. Essentially, it's the good bits of Borderlands condensed into the instanced mission style from Warframe, without long periods of driving and wandering around and chasing quest markers to break it up. Gearbox humor has always been hit or miss for me, but in Battleborn it's a solid hit. There's no nagging Claptrap (yet) to get in the way and the voice acting seems solidly delivered, both for the PvE encounters and the player characters themselves.
Overall I'd say it's not terrible. The PvE definitely isn't the focal point, but it's still something to check out especially if you're a fan of Gearbox (I'm really not and was pleasantly surprised). You can hop over to https://rsvp.battleborn.com/
and they'll give you a key for Steam or some console thingy if you wan't to be that guy
. It'll help fill the void for all the people out there who haven't gotten into the Overwatch beta.