For reference, we owned a '07 Odyssey Touring, test drove the previous gen Sienna & road tripped ~1000mi in this '11. The new Sienna has a significantly improved drivetrain. The engine is strong & passing is easier than in the Odyssey. The steering is accurate though lifeless. And the brakes are better than the Honda's. In terms of driving, the new Sienna & the Odyssey are equal & both are far better than the last gen Sienna. Everything else, however, seems not as good. The plastics are about the cheapest I've encountered outside a rental car. The road noise is far worse than the last gen's. The 2nd row lazy-boy seats are a useless gimmick. The backup camera's display is microscopic.
Great acceleration. Good handling for a minivan. Comfortable ride, but a bit stiff-legged on bumps due to the run-flats. Easy entry/exit in the rear. Minivan versatility. Best looking minivan exterior (for what that's worth).
Road noise. Cheap plasticky interior. The lazy- boy seating is useless (for enough room to raise the footrests, the seat must be slid all the way back & that eliminates the 3rd row legroom). Poor HVAC controls (they are asymmetric; one's a dial, the other buttons, making them hard to find at a glance