I have an 06 vectra 1.8i sri and I have had it for 3 years now and couldnt be happier with it. I have the satNav version. The average mpg showing for the last 37000 miles is 37.2mpg which I think is good for the size of the car.
Its not the fastest car I have ever driven but it hasnt given me any problems and I haven't got bored with it yet. I am easily pleased where cars are concerned but this is a big improvement on the focus I had that I couldnt wait to get rid of. Buy it if the price is good - I would buy another.