Yep. It is true it has been that "brains" and "pain" have been an object of debate since nerve studies have been developed.
The bodies of crustaceans are divided into segments, and there is one ganglion per segment. Each ganglion receives sensory and movement information via nerves coming from the muscles, the body wall, and appendages such as walking legs, swimmerets and mouthparts. When this information reaches the ganglion it is processed on the spot, enabling a faster response than if the message had to travel all the way up to a centralized brain and back. So they certainly react to and sense their environment by stimuli.
The debate about pain comes from how nociceptors are interpreted in inverts as opposed to mammals. I've seen studies on nerves from inverts theorizing they respond to sensation and not pain- so that is probably why I fall on that side of the fence. Although in full transparency there are also studies that theorize pain may occur. Neither way is entirely proven yet.