Prior address had very low signal - was a bungalow so quite an easy install to fit antenna up on the TV aerial mast and feed the cable into the loft. Fitted internal aerial in the airing cupboard and voila... full signal on both SIMs BT and Vodafone on my dual SIM phone. About a month before moving to a house the unit died... had to leave it as had some personal issues around the time but after moving, found new house had 0 bars on BT and 1 bar on Vodafone indoors. Needed the booster. Contacted Mobile Signal Boosters via email and they had a replacement unit shipped to me, though not actually installed fully as of yet (since moving I need my ladders back so I can get up to roof level) but positioning antenna up in the loft and running the cable down to the unit ad-hoc, not great aerial separation that is a main requirement, but still getting two to three bars on both SIMs. I expect when I get the external antenna fitted properly and wire fed indoors though the roof space, and booster unit setup and antenna mounted in landing cupboard, it'll be good.
So, support I got was great considering just a few months left on the two years warranty, and though a considered purchase of a sort, essential considering the signal we're getting here in the new place. If you work from home, and rely upon your mobile signal for calls, it's almost a must-have consideration. Just bear in mind installation requirements and that separation between the two antennas.