I have one for Mum as I have a steep nineteen thirties staircase. Mum finds descending too nerve wracking following a fall (heart blipped while she was walking up and she came down headfirst). She took quite a while to get used to the lift - put the seat down, turn it, put the foot rest down and put the seat belt on, then slide the switch to move it. She's fine with it now, even on her more confused days.
Having fan steps at the top or bottom of the staircase makes the lift a lot dearer because the rail has to be custom made to fit the fan. I went with Stannah as their rail went closer to the wall round the fan than the other one I liked due to configuration and type of rail. The rail bolts to the steps, not to the wall; you need an electrical socket nearby for the plug. Rails run on direct current to charge the battery in the chair so they come with a much bigger charger than a mobile phone that has to be accommodated.
You can save a bit by having a second hand, refurbished chair, and a refurbished rail if the staircase is straight.
The lift is serviced annually and that's another cost.
The three companies that came to quote all asked if Mum's dementia would allow her to operate it safely or they wouldn't install it. I said yes, but as Mum was in hospital at the time, they didn't meet her. The hospital OTs thought it a good idea once they saw my stairs, but warned me there would come a time when she wasn't safe to use it on her own. You can lock them with a key and remove the key to stop the pwd using it at all when you're not there.
The remote control is useful if you want to send heavy stuff up and down the stairs - I balance my ancient and heavy sewing machine on it and full suitcases. Every child who comes to the house will have to have a go on it!