PSA: Mei's slow is currently bugged as of Patch 1.10.0.2.

[Tanooki]

Currently, Mei's primary fire and ult are not slowing down targets when used. The freeze affect is still applying, just not the slow. Source: reddit

I thought I noticed this yesterday when playing Mei, but I just thought I was doing really poorly with her, and not hitting anyone with my primary fire.

 

[Minty]

Honestly, it's not too big of a deal. Freeze takes place so quickly anyway... They'll hotfix it soon.

 

[Treaty]

idc bc she is annoying when i'm playing genji

 

[Mr. Lemming]

idc bc she is annoying when i'm playing genji

I giggle anytime I'm against a Genji and they desperately try to deflect my M1 spray.

/and then the evil grin crosses my face...