I'm on my second hybrid (both been company cars), current one is around 1 month old and I do really like it. That said, if you're looking at this as an economy saving, if you're driving sensibly you will get in the area of 400 miles from a filled petrol tank. Sadly I don't have the ability to charge the battery right now, but when the car has had charge you are likely to get around 30-40 miles of pure electric driving.
The self-charging system absolutely drinks the tank and can't recommend it, but I don't have enough experience to tell you if when fully charged, it impacts the petrol mileage.
To drive? It's really fun, the older model of hybrid that I had which was a 19 plate from memory handled quite poorly. This one on the other hand is much nicer but I'm not sure if that's down to it having a more sportier profile.
Let me know if you want anymore info on it, happy to help.