Ooooh we have a Bongo and we love it. We only use it at weekends for going away but it's neat enough to use as an everyday car I would think, it's not much wider than your average family car. We can park in normal spaces too.
We have fully comprehensive insurance, which was ridiculously low at something like £230 per annum. That's just for weekend driving though and we found that through the Bongo Fury website.
We have a back conversion, which includes a wee sink and hob, gas tank units and the bed when folded takes up the whole back space, which is big enough for 2 adults. We did get an inflatable mattress as the head rests tend to stick into your kidneys as you try to sleep!
With the bed folded away we have a full bench seat and two fold up single seats at the back. There's also a little kitchen table that can be assembled.
The electric roof is fab, it's more like a tent experience actually, and I think you'd be hard pushed to get more than two kids in there.
Disadvantages are: I've just taxed it for 6 months at a cost of £99. It's a 2.5 litre diesel engine which has permanent 4WD. The average is 30 MPG doing 60 MPH.
The battery runs down really quickly if you use any of the electrics (quite a problem with the roof, air con, lighting at night) so we're thinking of investing in a leisure battery for this purpose. I would say this has been the bigest problem and we've called out the AA on more than one occasion.
Also there's no toilet in ours, although I know some conversions have a porta potty included.
I think the best advantage for us is that we're not restricted to campsites, and Scotland is a fantastic place for wild camping. At the weekend we drove up to Crinan and then down 14 miles down a single track road to an ancient jetty overlooking the sound of Jura. It was only us, the view, and a few sheep for miles and miles. Bliss!!!