Few thoughts.
There is an optional "jump" seat available for the H1 to extend the passenger capacity to 5 (maybe 6 with small children). Basically a seat that sits in the area between the rear passenger seats.
Smell. Never have noticed a diesel smell.
Noise and comfort. This one has probably been beaten to death elsewhere but an H1 is not as quiet (it is a diesel) or up to the H2 in creature conforts (though with 2004 changes maybe).
Now, having driven mine for several months (not a daily driver) I will say that it handles well on the road. No problems parking or getting in and out of places. Visibility is much better in the H1 (backing up). Comfort is not bad at all. The real secret to a happy H1 experience is making sure your tires are balanced and you have the proper match of tires for purpose. If your daily driving on highway you want GSA's, not MT/R. It's really a matter of making sure the application is right. This goes a long way to ensure the best experience.
Better gas mileage than my H2. Not much but definitely better. A few months back I would have said diesel was cheaper than gas but that's changed recently. Diesel here seems at least to be price stable where gas moves up and down a lot.
Hope that helps...
2001 H1 Opentop
Former 03 H2 Adventure Series
http://homepage.mac.com/babiak1/