I have a 2010 3.5 Impala. about 62k on the clock.
I'll make a quick no order list of observations.
There isn't much to look out for beyond the transmission really that you can do something about. Mine did suffer a leaking head gasket on the backside of the motor. It was an external leak and didn't notice until my coolant ran low. No damage but very annoying. Extended warranty ate that one.
Front rotors don't have a long life expectancy on these cars.
The PCV I don't think is servacable on these cars and part of the valve cover.
Beware the fitting on the trans cooler lines, one of mine leaked. Warranty ate this one too.
Driver seat is flimsy, don't beat on it, if its cloth.
Dash pulls away on the driver side a bit around the vent.
Car may eat rear tires, there is a TSB about this but only for police and taxi I think. It's a camber issue. Mine doesn't exhibit this.
Found mine to be quietest on Mobil 1 5w 30. This motor was Dexos 1 for you just because everything that year was. I'd still run a good oil.
Beware the oil filter adapter gasket, they leak.
Don't pull on the door handles too hard in freezing conditions, they are flimsy.
Make sure your air filter box is really shut. It's easy to leave the bottom of the gasket sticking out
There is a TSB about the magnets in the trans fluid pan. Not sure of number.
Some complaints with throttle body assembly and related sensors.
The console shiftier cars can have an issue with wiring to the shiftier being too short and ripping out when put in the bottom of the range. I have a column shift car so I can't confirm. This can immobilize the car obviously.
Watch your coolant crossover for leaks, its a dry manifold car but this gasket does tend to fail.
You could have bought the Malibu in my signature that destroyed a valve seat along with the rest of the carnage at 70k miles. No more GM for us after these two.