I went down and back up last summer.
In general the roads were in good condition. Having said that, there's always going to be some gravel because they're always working on and improving it.
The further north you get, the more frost heaves you'll find - SLOW DOWN. Sometimes the gravel is preferable because they can grade it flat. There's not much they can do with a frost heave in the pavement.
Most of the people who have problems were driving too fast - SLOW Down - there's just as much to see in Canada as Alaska. Alaska will still be there when you get there.
Bill