Mostly wear and tear, but a few other minor faults as well:
Exhaust and heat shield had to be replaced had to be replaced shortly after the car was purchased.
Suspension bushes had to be replaced.
Brake pad warning light keeps coming on as the sensor has broken (I just ignore it tho as I know my brakes work!)
Sometimes suffers from rattly tappets for the first few seconds on cold starts (A common Ecotec / Red Top problem).
Driver's door lock broke.
Performance is very good considering the weight of the car, if you keep the revs up. 0-60 takes around 8 seconds so it's quicker than its closest rivals and it should top 130mph. The engine sounds really good, but the close ratio gear box could do with a 6th gear for quieter motorway cruising.
Ride and handling is quite good, but there's quite a lot of body roll and understeer when it's pushed really hard. The sports seats are very comfortable and supportive.
Build quality is very good and the whole car feels very solid - better than the Vectra B and Mondeo in my opinion.
Economy isn't too bad - it averages about 30mpg.