The tower offers a nice, 360 degree view of the area. There are two viewing decks. The upper is open air. The lower is enclosed. I am not sure that I would consider it a bargain, but you can get coupons at the Hot Springs visitor center or in one of the Arkansas travel guides. In additon to the view, there are small exhibits depicting the history of the area.
One important note: The upper level is infested with wasps! If you have allergies or a strong aversion, stay in the enclosed area.