In-shower body lotions are not really a new product out there, I tried this one a while ago. 
I wasn’t sure what is the purpose of in-shower body lotions, I thought if you want to use a body lotion you'll do so after you get out of the shower. You need to use shower gel before it, so it’s not both shower gel and body lotion in one.  
This one I tried is from Nivea  and it’s for normal skin, there is a version for dry skin as well. You use it after your shower gel, just apply it all over your body and then rinse it off.  
Texture is a little weird until you get used to it, like normal body lotion just more oily. Be careful when you use it, your tub or shower will get really slippery so it’s easy for you to slip (almost happened to me). 
Also,  make sure to clean the shower afterwards to avoid accidents in the future. When you get a grip of it this product is easy to use.  It makes my skin soft and gentle but I have to rinse off well otherwise I feel like there is residue on the skin.  
I can’t say it’s as good as regular body lotion, definitely not my first choice for everyday moisturizing. 
Other thing I don’t like is that you do need to use a lot of product  to cover your whole body so you use it up quickly.
I only use in-shower body lotion when I am running late and have no time to use normal body lotion. In those cases it's really a life saver. Other use may be for people who have really dry skin so they can use it in the shower and then use their regular body lotion as well for added moisturizing.