Bought this for a family trip to France.
Really easy to fit (in the Go Outdoors car park!) and looks great on the car too. It fits well on a standard set of bars on our Saab 9-3 or probably any similar sized saloon. Size-wise, it fitted on large, a medium and two small suitcases (the IT luggage type) along with a few boxes of nappies and other small bits and bobs. It's sturdy enough and feels really strong when the lid is down. There's even a little extra clip at the front for peace of mind on the motorway.
When it came to driving with the 530L box on, I could hardly tell it was on. A little noise was present but I think that was more from the roof bars rather than the box.
All in all a very good box. Put its usefulness with the price you pay and this is a must have, particularly when you put it up against the Exodus box with 60 litres less room.