Main strengths: Capability to Teleport her team, Additional defense (shield) for her team, Controlling areas, Good damage for support (short ranged), Decent poke.
Main weaknesses: Low mobility, Needs to charge her ult before first death, Predictable.
Favourtable maps and modes: Best as defender on Capture points (on first point) - after the last Symmetra changes she is quite viable on all maps and modes.
Synergises with: Tanks mostly.
Good against: Genji, Tracer, Mercy, Lucio, Reinhardt, Winston, D.Va
Countered by: Widowmaker, Mccree, Hanzo, Reaper, Zarya, Roadhog