We've spent three summers up there and we are headed back for the fourth this year. Highway 5 in northern California is in worse shape than 99% of the Alaskan Highway!
Once you hit Canada slow down and watch for frost heaves. They will be your worst enemy. That being said, the scenery and animal sightings will keep you slowed down anyway. We enjoy the drive through the Canadian Rockies as much as traveling around Alaska.
If you are looking to drive at freeway speeds this probably isn't the trip for you. If you like to drive the two lane roads across America experiencing the small towns and slower pace of life this could be the trip of a lifetime!