Significantly less reliable than the 1.4. Faster, thirstier. Runs a higher internal temperature, which has a tendency to age plastics.
I would not discount a 1.4 as you will get a better car for the same money. I would also be very wary of an early TDI as you don't get Euro 4.... but either could get a DPF if necessary. I would still opt for petrol over diesel if you need long-term city-entering capabilities and if anything, the 1.4 petrol is the simplest and most reliable of the bunch.
- Bret