Minivans have always been more about function over form, but the Sienna tends to somehow look both awkward and forgettable. The big grille and slanted headlights look like the designers tried to make it look sporty and aggressive, a notion that need not apply to minivans. However, they seemed to have only partially committed to that idea before giving up and going to lunch. SE models do have sportier side skirts, but it isn't enough to improve the overall look.
It seems that the interior design of minivans these days aims to make the driver feel like they're in a spaceship as opposed to a boxy kid-hauler, with a plethora of screens, dials, and technology that look cool and interesting. The Sienna certainly has that, but the real importance of a minivan is practicality. "How much stuff can you store where, and how easy is it to do it?" is the mantra of the minivan buyer, and the Sienna answers that question well. The van can hold a lot of stuff with the seats folded, although the seats do not stow away like you see in the Honda Odessey and Chrysler Pacifica.