You can use it at room temperature but sometimes it is to cold to enjoy so you will end up having a cup of warm water and wash cloth to dip it in to warm up the toy. If you enjoy cold things then try putting the toy in cold water.
I’m not knocking them but sometimes it just is to much. Some Glass toys can even break if they get dropped. Be cautious with these toys because I have heard war stories of how they break and just unpleasant things happened.