Yes, this is right near the train station, no hills involved. Could be a bit noisy, take a look at the street view on Google maps and you will see it is right where several roads meet at a fairly busy intersection, but as a place to do day trips from it will be very convenient.
I have not stayed at any hotels in Thun, so can't speak from experience, but one that I would choose based solely on the location is the Hotel Aare Thun. It sits right between two branches of the Aare river, no traffic noise, maybe people sounds and of course the sound of the river. Years ago this building was actually a department store (Manor) and their restaurant had a large balcony with great river views. It was a favourite place for our family to grab lunch.
You would have to compare the cost and reviews, etc. It is near the train station as well as anything you might want to do in Thun (castle, old town, etc.).