It definitely looks fun, but I am not too fond of TF2, and Overwatch looks a lot like it as you said. I would've prefered if they announced Warcraft 4, but that was of course unlikely since Starcraft 2 is still running. Actually, just give me any RPG or RTS, that would've made me more excited for their next game than I am now.
It makes sense though, lately Blizzard has been trying to branch out with titles like Hearthstone and HoTS, and now they're trying to get a slice of the huge FPS market.