 We upgraded from a 2003 to a 2004 Toyota Sienna and there is a BIG difference.  The vehicle is like 6" wider and longer and it is so nice.  We were not able to put a rear-facing car seat in the second row of captains chairs in our 2003 but the 2004 fits it nicely and my wife and I are both over 6' tall.  The stowable rear seat is very nice too.The gas mileage is right around 20 mpg which could be better.  It has plenty of power though and the ride is nice.  Some of the issues you'll likely run into with a 2004-2010 Sienna: sliding door cables will break, the dome light switches on the sliding doors will get water in them and go bad, a clicking noise in the steering column will develop and/or stiff steering caused by a corroded u-joint in the steering intermediate shaft, and also the right headlight fixture of all these vans is prone to have its seals go bad and for water to leak in. I repaired all these issues myself though. Oh and I've had a front and rear spring break. BUT, the van has almost 200k on it and I'm confident I'll get to 300k with this van. So we are still pleased with it.