A "hotspot" addition to a cell phone is fine if you have good cell phone coverage. I do not have a Travlfi but seriously considering one. They use all three cell phone towers (ATT, Verizon & T-mobile) for coverage which is better than just your cell phone. I've been reading reviews on other RV forums and the majority are very favorable.
I just came across something else that is similar to Travlfi. It is called Simo Solis Lite. The difference that I see is that with Simo you buy how much data you want and it never expires. So no monthly subscription. Has anyone tried this one? Opinions?