We're 7th level in our 5e campaign, and we've been playing it since beta. We have two rogues, a barbarian, a wizard and a bard (me) in the group.
Rogue #1 is melee-based, and usually gets off at least one sneak attack every combat. It's solid damage, but it hasn't overshadowed the campaign at all.
Rogue #2 is ranged-based, and has the SS feat. When he does his SS thing + SA, he usually drops most things he hits it with. I won't lie, we're 7th level, and he will drop 40+ points on a guy in one hit. The problem? He doesn't always hit. That -5 is painful. But it's usually a once-per-combat thing when he does it, hit-or-miss. So OP? Not really.
We've found the Wizard to be kinda underpowered honestly, unless he is able to AoE. (fireball, etc; hard to do usually unless it's an opener and he rarely wins initative) So he is usually crowd controlling with Slow or Hypnotic Pattern. Generally speaking, single-target DD for a wizard is very poor this edition.
Bard (me) isn't a damage-dealer, he is much more about controlling the field, and making damage happen by casting Dissonant Whispers, provoking AOO's from the melee. He's also the healer, so, ya know, I usually heal a lot.
The broken one? The Barbarian with GWM. Holy crap. We found a pair of gauntlets of ogre power for him, and it's been insanity ever since. He pops GWM + Reckless Attack (so he usually still hits, even though he has -5), and then he gets two attacks a round now, because he's level 7. He usually swings for 30+ points a swing with his greatsword, meaning he drops enemies a lot. -Oh, they died? I get another attack as a free bonus action.
So to answer your question... a big fat NO. SA isn't overpowered this edition. Not by a long shot.