Just feel how good the clutch is and how smooth it shifts. Also, check how will the car picks up and goes after shifting. To make sure the power is transferring OK through the drivetrain.
Good thing is, transmission fluid is easy to change on these manual transmissions.
You could also get stuff in the future to improve your shifting experience. Like short throw shift, shifter bracket/hanger, and transmission bushing insert. All are fairly easy to install and are relatively cheap vs. some of the other mods.