Obvious check, starter clutch sprag, it's engament and ability to turn the motor.
There was updated material specification for them .... should be in there on later build apparently ... no way to really check parts. It should though engage instantly, not hear it dragging without crank turning (slow moaning / screech) and fire it pretty promptly. Not helped if battery is low or not up to scratch in giving the sprag a good "hit" to get bite and rotation.
If slow from battery, don't keep doing it as it won't help lifing.
Fork seals, check for weeping as they can get a bit gummy.
Rear brake caliper gers alot of water as underslung .... give pedal a good squeeze, then roll it back and forth to asses release. Not hard to service, with two slide pins and lubrication of pistons etc. It will need reasonable and regular inspection if used year round, though not a show stopper.
Tires, check for alignment as wheel beeds are very well toleranced and resistant to popping the tire up onto correct place to run true. They're tubless too.
Must run antifreeze all the time, not water.
Generally tough and reliable overall.
Great torque from motor, like a diesel bus

don't need to rev much for pace. Feel very different to many fours in character, can feel a bit top heavy with full tank, though steer very neutral considering they're not race rep type bike. Easy going to ride, you've got to load the pegs and muscle the bars if you really want to get them moving fast.
Nice bike to own.