As Barrio says regards noise and vibration, but be a bit cereful, much of this can be caused by poor condition, chain and sprockets, failing pedals, loose crank arms, loose motor bolts etc, etc.
The symptoms of bearing failure will depend on which bearing is failing, but the most common bearings to fail are the main motor bearing and crankshaft bearings. If you hear a grumbling or "coffee grinder" noise, it will normally be the main motor bearing. If you feel play in your crank arms, it could be either crankshaft bearings, main motor bearing or both.
A quick check can be done by slipping the chain off the front sprocket and turn the pedals forward as if you are riding. By doing this, you are turning most of the bearings in the motor, but most importantly you are turning the main motor bearing and can listen for any noise above a quiet whirring. By then turning the pedals backwards, you are now only rotating the crankshaft bearings and freewheel gear bearing, so noise or rough feel here will normally be crankshaft bearings.
Active Line plus 2nd Gen are virtually identical to Performance Line and fail in the same way (Please remember, most makes of pedelec motors currently fail in the same way, not just Bosch)