I had the 9110, 9210, and 9500. None of them really made sense as connected devices because data services were so slow. Web pages would literally take minutes to load, and for heavy use you were paying by the byte.

The main benefit was a nice(ish) keyboard for texts and emails.

I once wrote and emailed in a consultancy report from the back garden of a pub, just to prove I could. But it's not something I'd have been happy doing regularly.

If Psion had somehow added mobile data to their Organisers they'd have killed this market.

https://en.wikipedia.org/wiki/Psion_Series_5

The main thing these devices did was normalise ARM and pocketable form factors for serious mobile use. But they were really micro laptops and not large mobiles.

They were more like very early versions of the MacBook or Air. The iPhone - rightly - went in a different direction.