I had precursor to this at home , the BBC Micro.
I remember using the Acorn Arch at school, we had a lab of about 20 of them.
From what I remember no crashes, viruses or anything of the sort on any of them.
I remember at the time the pressure on the school at the time to switch to IBM PCs "because that is what business is using", which in hindsight feels like a shame.
The did crash - quite regularly, but it was usually user error :)
They did also have viruses, but they were usually funny and harmless.
However, business wasn't using IBM PCs in the UK at the time. They didn't get a look in - pretty much everyone was Acorn in the UK.
My father was the FIRST major PC clone importer/builder in the UK (waaaay before Dell even got going here) and he nearly died from lack of sales a couple of times as people were either quite happy with their ancient Acorn kit or bought new Archs when they came out. The PCs of the day were a bag of shite, unreliable and unproductive and people knew it. He now sells Dell kit which is a bag of shite, unreliable and unproductive. How times change....
Unfortunately for Acorn, the tables turned as RM PLC got into the government and promoted the PC, businesses hit the Internet, Windows 3.1 came out with Winsock, Netware was usable and interoperability with the US was required regularly (which was PC all over).
Game over. Momentum destroys superiority.
As for popularity outside the UK, NL, DE and NZ had a fair amount.
I remember a composer I knew had one because of Sibelius, this was in Australia. They weren't unknown here but were certainly rare. I do remember that RiscOS was a thing of beauty though, very very sleek.
I used to sing with one of the authors of Sibelius, who was a very talented guy. I remember him bemoaning the cost of an Apple dev kit when they were looking at porting Sibelius to the Mac back in the early 90s.
One of the great advantages of the Acorn hardware was that there was no barrier to entry if you wanted to program them. Perhaps because their initial focus was computers for use in education everything you needed was always right there. You could sit down and start typing code.
If you wanted to write C (there was a C++ compiler based on CFront too IIRC) then you had to buy a compiler, but people achieved a huge amount with the tools available on stock machines.
For a number of years, Acorn had the most powerful desktop computers in the world at a reasonable price, but they failed to capitalise on that advantage & were eventually overtaken by the MS/IBM/Intel juggernaut.
I still remember being in awe of the effortless full screen scrolling of scores in Sibelius on RiscOS, so far ahead of the offerings on PCs of the time. I remember thinking the concept of RISC was a bit of novelty though, yeah I may have been wrong about that.
From what I remember no crashes, viruses or anything of the sort on any of them.
I remember at the time the pressure on the school at the time to switch to IBM PCs "because that is what business is using", which in hindsight feels like a shame.
Were these things popular outside of the UK?