Had great prior experience w/ Honda Accord so purchased vehicle over Toyota, Nissan. Traded in '98 Caravan driven for over 100K miles. Solid ride, standard options, and Honda reputation drove my decision towards the Odyssey. Cylinder deactivation is a plus. Very disappointed in quality though. This is a grocery getter, and not driven hard. After 9K miles, there has been 4 trips to dealer for alignment service, resulting in premature tire wear, 2 trips for steering knock (which by the way is a known serv bulletin issue that requires special lubricant on the steering column), now a rattle in the sliding door. This is a Honda? I actually had less issues w/ Caravan. Now test driving a Sienna.
Feature / Content vs competition which offers ala carte or part of more expensive option packages, handling, looks (for a minivan probably the best looking), interior design and space, much appreciated storage spaces all throughout, and small touches like fabric lining and spotlight in center.
Address quality issues (review blogs, others having similar issues), durable interior plastic (easily/permanently damaged), gas mileage, engine, tire noise. Most items not noticable during initial test drive / honeymoon period, some that provided glowing reviews will probably take some of it back.