Is it any good to visit Alaska in wintertime?

I was supposed to take a vacation to Asia from December to January, but obviously had to cancel it. I thought of just traveling domestically to somewhere I've never been to.

A google search came up with the Winter package from Alaska Rail Road. It's a 'daytime' train from Anchorage to Fairbanks. There's some 'day' tours I can take in either ANC or FAI, then I have to buy an air ticket from FAI back to ANC. I was told that in Winter, there's only about 6 hours of sunlight in AK. But the trains and tours operate through winter, so I guess there's demand (I suppose mostly for Aurora tours).

Any insights?