I had a very similar experience. For 1995 it was really quite amazing! Loved how quickly it connected ("I never have to listen to a pair of modems sniff each others butts again!"), and that I could place/receive a call while still being online. Also, the voice quality really was superior, even when receiving a call from a regular POTS call on the other end.

Unfortunately, after the first year of having it, US West (Omaha Nebraska USA telco) started "actively discouraging" ISDN (source, I worked at US West at the time and was asking a sales tech about it). I had wanted to move to a larger apartment in the same building, but doing so would have increased my ISDN cost from $40/mo to by-the-minute $400-ish/mo.

I used a Motorola Bitsurfer on Linux. But my other computer, an HP 9000s712 ("Gecko") had an ISDN modem that was SCSI. That seemed like a weird choice, but their serial port was only rated up to 115.2K so it was the only choice for 128K.

In my locale it was much cheaper, because of massive push via subsidies from former gov-telco. We also had 2 x 64kb/s channels, for 128kb/s bundled(dynamically/on demand), plus signalling channel. Since it was so widespread you actually had a chance to enjoy very good voice quality, which often is still unsurpassed, today. Especially regarding latency. Again because of the wide availability, the not so special phones weren't that expensive, and adapter boxes neither. But nobody wanted these anyway, because old phones didn't give the good voice quality.