I have been on CPAP for about 15 years. The equipment has changed considerably in those 15 years, not always for the better. The filters on my original Respironics CPAP were many times larger than my Series M CPAP. The white filter on my first CPAP would last for well over a year before it needed to be replaced. My original machine was fairly loud and had two external controls; Power On/Off (a momentary contact rocker switch) and a ramp selector switch (a multi-position rotary switch). The pressure was set with an internal Trimpot. My first mask had a headgear that made me look like I was wearing a pair of ladies' knickers on my head.
I've been on CPAP/BIPAP for about two years. I guess I was one of the lucky ones because I took to it right a way. I did have mask issues ( leaking) and I had a devil of a time with the pressure leaking out my mouth. So I started with a nasal mask, then a full mask and taped up my mouth with blue painters tape. On my second visit to the doctors we did another sleep study and tried the new ResMed Swift FX nasal pillows system. And went on BIPAP. What a difference, the nasal pillows were very comfortable and with the BIPAP I no longer have to tape up my mouth. Sleeping like a baby.