Other than a couple of recall items shortly after we purchased in early 2004 we have had no reliability issues, repairs, etc.
in 2004 the Sienna had optional side curtain air bags only on a couple of top end models & crash worthiness tests, as I recall, were among the best. Since 2006 I believe Sienna now offers side curtain air bags on all models.
The fit & finish, quality, attention to detail is better than North American & other Asian competitors.
Having never driven a van prior to buying in 2004 I expected it to handle more like a full size vehicle. The Sienna handles more like a car than I thought it would.