Left rear sliding door rattles.
I can honestly say that I am really enjoying this vehicle. I was very reluctant to purchase a GM mini van, but the price and incentives were too hard to pass on. Since we have owned (aug/04) the Montana it has been a no nonsense practical family mover. My wife has come to love this van and feels very safe driving it in all road conditions. It is very easy to move the kids in and all the items that come along with them. I can say this van delivers on value for money and genral quality and reliablity has far exceeded what I thought I was going to have to contend with.
Bought an 04 Montana Extended in August 05 at Carmax mainly for the 8-passenger capacity. Very satisfied with it, though it quickly becomes obvious where GM skimped on materials or took shortcuts -- you can see the seams in some of the plastic moulding, for instance. Fortunately, these are places where durability doesn't matter (I hope). I'm expecting some scuffs to start showing up soon. The engine, though not the most powerful, really shines in the miles-per-gallon department. Friends with a similar GM V-6 tell me it's solid and reliable. The tilt-forward middle row seat (required on an 8-pack minivan) works just as easily as Toyota's. It's too bad they discontinued the large van to build one that's supposed to be "sporty." If you've got a big family, find a low-mileage 2004. With 2 kids, you can get away with a new one. Hondas and Toyotas may have all the bells and whistles, but these do what a minivan needs to do, and have an engine with a good reputation. Since they don't win any of the comparison tests, they can be bought for a lot less.
UPDATE, I now have 60K km's on the van and so far so good. We have had nothing fail with this vechile. My wife drives this van 90% of the time with my 4 year old and 1 year old and I have total confidence in the van. I know to expect some problems, but I will say driving 60K km'a and no issue is a great success. I think we will keep this van for a long time and reccommend it to anyone looking for an affordable mini van to the over priced Japanese mini vans.
Another update, just passed 65000kms and I have replaced all four tires with Michelin Harmony's what a difference! The van corners better and handles way better than with the stock tires. I highly reccommend these tires, they cost a little more (about $155CAD) but highly worth it.