Ok, so I had some time with the game, and by that I mean it was the only game I played fir the entire weekend of the stress test, and I gotta say, Overwatch is awesome. It's really a lot of fun, and there was only like 3 maps and 2 gamemodes (sometimes they mixed them in a single map.) It plays like my original assessment of TF2 mixed with Monday Night Combat, but Blizzard has managed to make the game "feel" like it's own game. Even though the concept(s) behind Overwatch is inspired by ideas from previous games, it still felt like it's own game, and I was always wanting to play "just one more" match. Everything seemed smooth as silk - the framerates, the controls, the gameplay, etc. was all responsive and functioned flawlessly. There was also controller support with button remapping for those interested. I've heard complaints about the UI, but personally, I didn't really have a problem with it.
I heard in a video prior to my experience with the game that "there is no best class," and this seems pretty accurate. I'm not going to get into the viability of Overwatch as a competitive game or a esports contender, because my competitive gaming days are long gone, but I will say this - I didn't play every character, but I did play most of them, (everyone except Genji and Tracer) and every class plays their own way, even among the individual classes (offense, defense, tank, support) and they each serve their own purpose. I did find that certain characters may be better suited depending if you are attacking or defending, but even still, I never really saw any character that seemed OP, nor did I see any character that seemed overused, at least on a per-game basis (like no character stacking among teams) which brings to me to my next topic. There is a simple yet interesting concept Blizzard has implemented, which is any player can choose any character. If you want 6 of the same character on a team, you can do that, however as I mentioned, I never saw it in action. You can also change your character throughout the game rather than being stuck with your initial choice, like in a MOBA.
I'm definitely going to be picking this game up when it launches, but I will be getting it on Xbox One, where all my gaming friends play.