I love the new Mei. I always loved Mei but now she's even more fun.
It's not like you snipe people all the time, but out-sniping a Widowmaker once in a while is fun, or even helping your hitscan deal with a Pharah. Overall you do more damage, so you build your ultimate faster. You might get 1 more per round or so which can make a difference.
I haven't played much since the LFG and Endorsement went live, but pretty much everytime has been good., almost no toxicity.