My 4-5 hour wait at the border was not normal, I've definitely done the trip much faster and I've done it many times as I have family in Santiago. Just warning that in January there was construction, and it's possible they have not finished yet. It is a beautiful trip, though and I still reccommend it. Make sure to bring a sweater for when you're at the border though because even though it is summer, it will be pretty cold on the top of the Andes, and I almost always seem to forget!
Here's a picture of that road into Chile: