Since they got rid of allowing you to play as multiple heroes in Quick Play, I couldn't tell you how many times my team HAD to have a Sombra player when I really kinda wanted to try her out.
From the limited times I've got to play as her (I know in the Arcade there's a mode that allows you to play multiple heroes), she's not really... great. It's not that she's hard to play, she's fine for me. They just overhyped the crap out of her and she's not really that great. But she's not really overpowered or underpowered or anything. She just, to me, feels really bland. Like, I'd rather play Tracer over her... even though she's not really Tracer 2.0.
My only complaint with her is that you cannot hack health packs until the round actually starts. So if you're playing as her on defend, you can't do jiggly squat until the opposing team comes in.
Oh, and did anyone bother to get the Oni Genji skin? Once I get home from Ohio, I'm definitely going to log in to reclaim the skin. It sucks that this game can't play on my Mac. :-/