I played a couple hours the weekend before last. It has potential but the beta is beyond dead as far as players go. I never found a matchmade game, had to rely on LFG instead. Once we had a group of 4 we did consistently find a fifth from the Antagonist mode. I'm worried about how many players the full game will have, but the game and it's beta have hardly been advertised so maybe it'll be fine. A low playerbase could be a fatal flaw, as you either have to play solo or be able to find a full team of 4 to even play.
As for the game itself, the gameplay is fun but the loot system needs work. At the end of a match you all pick your rewards and they're split between players if more than one person picks the same reward. Like Pick between 100 gold, 100 character points, or 100 something else, and if 2 people pick one it's only 50/50. It seemed like the rewards themselves were pretty light, with most of the things I could spend points or gold on being pretty expensive when compared to the amount you get per game. It does look like character skins are connected to microtransactions, though I don't know if you'll be able to earn that currency in game
The menu was buggy and somewhat unclear, though these I think are just beta issues. It seemed like you could unlock more levels but they don't seem to be there, or they weren't unlocking for some reason. We had menu options disappear more than once requiring a game reboot.
Finally, I'll talk about some gameplay thoughts. The core game itself is fine, though some of the special abilities each character has are much more interesting than others. It's designed around teamwork pretty heavily, if you get surrounded alone you are screwed. Boss battles are well designed and fun. The levels themselves are pretty linear and enemies spawn the same or very similarly every time you play, so I don't know how we'll they'll hold up for the multiple replays the game intends for you to do. Maybe they have plans for this, modifiers or randomized enemies or something. Normal players have a set number of lives, if you run out,at least one person has to survive for a timer that increases each time you burn all team lives, and you fail if no one survives.
Lastly, the Antagonist mode probably needs some changes. It works like Counter-Ops in Perfect Dark. A normal squad of 4 playing the normal mission, with one enemy player with infinite lives trying to stop them. In theory it's cool but the enemy isn't powered up in any way, so if you're paying attention they aren't much of a threat, usually at best they kill one person and the rest of the team wrecks them in return. There is one character that I think is designed for this mode, because her ability is near worthless against AI. If she focuses on an enemy for a set amount of time, she becomes invisible to that person. That combined with a sniper that is good playing as her could be a real threat, otherwise I think you'd have to be really good with the other characters and some just don't seem viable in this mode.