At higher levels of difficulty with difficult mission modifiers, or in elite deep dives (the weekly, difficult, set of special missions) I've definitely felt stressed - but the good type of stressed?

It's never been a salt or rage inducing game for me - certainly if you've handled Overwatch at it's most frustrating you'll be absolutely fine.

I tend to mostly play with friends and in voice chat, but the game has a context sensitive ping and good visibility on where teammates are. It's definitely doable without. Just spam the V key and you'll be fine.

I'd compare it more to other horde shooters like left 4 dead, payday and killing floor in gameplay - but I think going from Overwatch to this wouldn't be too much of a system shock. Character classes excell in particular areas in a similar way to Overwatch.

The single player is very playable too - if you're looking to try it out before jumping in with people. You get a little robot friend to assist with the general teamwork things you'd normally get in a squad!