I use it professionally all the time. I work with arm a lot, and during the testing of customer software that is compiled for arm, I need an arm based Linux os to run and test on. rpi is the obvious choice. I'm very happy with the 4s performance, so I don't require the 5, but I'll still get one.

I also use another one for retro pi, which I imagine will benefit from the increased performance..

lastly, I have a small handheld Bluetooth keyboard with a track pad I use with a pi4 with a 3.5in screen hat and battery pack. the overall size and weight is much less than any laptop I have ever come across, and I use this when I go to cons. (although I'm looking at plantecom to replace this)