I just have to say how great the progression is in the MP. I'm constantly unlocking several things after every match, and almost all of it seems valuable, yet I don't feel like I'm missing out at all because of stuff I haven't unlocked yet. They definitely knew what they were doing here. I usually hate extensive unlocks (see BF4), but in TF2, I never feel like I'm playing just to grind xp to get something.
The camos are nice looking, and some are fun without being ridiculous and garish. So many callsigns and badges! The guns rank quickly, but of the six or so I've used quite a bit, none seemed useless or crappy without the unlocks.
They really nailed it -- the progression is FUN, not a slog, and it does what progression should -- makes you want to keep playing just one more match!
Can't say enough good things about the MP, except maybe that it's keeping me from the SP. It seems like a ridiculous thing to say, but I really feel respected as a player, not just as a potential supply drop, loot box, or DLC buying machine. I so hope this game gets the same momentum and legs that R6:Siege got through word of mouth and reviews.