Colmar is a beautiful little city with a beautiful little train station. We spent about an hour…read morethere before a train ride to Strasbourg, and while I would not recommend arriving that early with small children (we were walking from our hotel and didn't want to get caught in the rain), it was an attractive place to pass some time.
The exterior was storybook lovely, with a long red brick facade and a prominent clocktower with a green shingled roof. There were a lot of trees fronting the entrance that were decorated for Christmas. My three-year-old and I took a walk around the promenade out front, and it was pretty scenic.
There's nothing to do inside the station but wait, so plan to get in and get out if possible. The walk to or from old town is only about fifteen minutes. It makes sense to take the train to Colmar, and worth admiring the train station while you're there.