I just got it and have already put dozens of hours into it. I can definitely see it being the next big multiplayer game.
However, I already see some of the same problems that other multiplayer games have. Matchmaking struggles to make fair matches. There's toxicity when games start to snowball towards one team. Lots of players will disconnect midway through a match if they don't think they'll win. These things are common in pretty much every multiplayer game now but I wonder if Valve will find a way to mitigate it.