The Sienna has finally passed the Odyssey according to the auto mags, for the last several years the Odyssey has been rated #1 and is still neck-and-neck with the Toyota. My wife has a 2002 Odyssey, it has the nav system and has been a very reliable and practical vehicle.
We have had no mechanical/electrical failures in 28K miles, so far the only things we have had fixed are a piece of rubber seal on the rear hatch spoiler that was coming loose, and a seat cover that was scratched up by one of my kids (grrrrrr). Honda did both jobs under warranty, no questions asked. There have been 2 recalls so far on the van, one for the belt idler tensioner and the other to install an additional oil cooling nozzle in the transmission. We did not experience problems with either prior to recall.
I like the Odyssey very much, the VTEC engine is a blast and it is surprisingly quick and nimble, freeway on-ramps are FUN and that little V6 will really howl at high rpm. On twisty roads you would never think you were in a van. The nav system is pretty useful, and the seating and cargo space etc are outstanding. Can't beat the practicality for a kid taxi.
Only dislikes - the stock tires are extremely noisy, not enough to warrant replacing but enough to irritate. The road/wind noise can defeat the stereo at times, it should have had a few more watts and better bass speakers included.
Fuel economy is not bad on the highway, easily turns in 25 mpg at 65-70 mph, high so far is 27. Around town and in day to day driving, it averages 17 - much better than our old Suburban.
Summary: HIGHLY recommended
Attention: TDR Forum Junkies 
