I did a lot of shopping in the minivan arena and while I liked the Sienna, I didn't like the price. The '05 Odyssey's were just out, but again very pricey for what you get. I drove both the Honda and the Toyota, fully expecting to buy the Toyota. While I thought both were great vehicles, it was ultimately my test drive of the MPV which put me into the Mazda camp for good. Felt great to drive, good power and flexible interior. I've owned a Miata for years and it has been the most reliable vehicle I've ever owned... I'm counting on the same with my MPV. Previously I'd owned a Chrysler T&C and put over 120k miles on it; what a piece of garbage.
Rear passenger windows that roll down, fold away 3rd row seat, nimble handling, 2nd row seats that can be a bench or captains chairs, safety... oh, and it LOOKS a lot better than the competition!
If I had to be picky, the engine isn't as refined as I'd like. I had an Acura Legend with the "legendary" Honda 3.5L six in it, and the smoothness of that motor makes me long for it in the MPV. But the MPV's 3.0L gets the job done and moves the van along very smartly.