Boosters, such as the Weboost RV, do work for their intended purpose. However, in most cases you will only need one when out very far from a cell tower. Using a booster when signal is good can actually slow down your internet as they only use one input/output antenna and not MIMO (multiple in/multiple out). In most cases, simply using a better antenna with MIMO capabilities would be a better choice.
Have a look at Mobile Internet Resource Center to get a better understanding.
https://www.rvmobileinternet.com/gui...ular-boosters/
Unless you plan to spend a great deal of time way out in the boonies, or you frequent areas where you are many miles from a cell tower, I wouldn't waste money on it until I was sure I needed it.