CJ- The '04 has been absolutely bullet proof (knock on wood), approaching 60k miles and no issues. The thing with first gen MDX's is the tranny. They supposedly fixed it by MY '04. The tranny's would go and usually just out of warranty and cost $4-5k to replace. Many angry customers, so much so that Acura extended the warranty just on the transmissions to avoid a class action.
The '07 is a completely different beast, more TL-like. The '04 kind of drives like a mini-van where the '07 when you put it sport mode rivals the handling of my '05 TL BUT with SH-AWD. More techno goodies too.