I used to have a Zafira 1.8 petrol and I loved it, once you get used to the upright driving position its great. Very practical and spacious.
The only negatives are the gearing which is very short, which means 5th gear always felt like fourth, not ideal if you do a lot of high speed motorway miles, and a big blind spot at the drivers side front which means you regularly hit pedestrians(Joke!)
apart from that I loved it. I would certainly have one again, but I would perhaps go for the diesel version. The only reason I dont have one now is because I need to carry ladders for work and its a bit too tall for easy oading on to the roof rack.