Having spent 26 hours on a train, to spend 21 hours in Harbin, I can say it was totally worth it!

On the way to Harbin, I took the overnight train, and had a soft sleeper.
This was the nicest option, which I chose more out of necessity than anything else, but I have to say it was really comfortable. The ride went smooth and without a hitch.
Arriving in Harbin early in the morning, we first went to the Chinese Baroque district. This was a quaint area with nice architecture and some small markets and stalls. After the Baroque district we walked on the frozen river, all the way along the riverbank to the main shopping street. This shopping street was really nice, but very touristy. It had a lot of Russian influence. Examples would be the Russian architecture as well as many shops with Russian products and staff.
Overall, the city of Harbin was a really nice city, it was well maintained and clean (especially for a Chinese city).

The Ice and Snow World Harbin, the largest ice park in Harbin was amazing. It was absolutely breathtaking, with massive ice and snow sculptures, ranging from Angry Birds and Smurf village, to a giant Buddha and a traditional Chinese pagoda. It was really amazing.

Pictures do not do it justice, but they will (hopefully) follow soon!

Location: Beijing, China