Trying to ease the confusion.
I once used this analogy and it seemed to have worked then to clarify. It's far from perfect, but meh...
Symbian: Underlying OS, think linux
S60, UIQ etc: Front End, think gnome, KDE
If you had to go through 7 menu items to play a game, would you blame the OS or the GUI?
UIQ was awesome, way ahead of it's time. There was a huge user community years ago for the advanced devices like the (admittedly oversized) Motorola A920, then A925 and A1000, and the P9xx series as mentioned above. We (The Moto crowd) waited and waited for Motorola to bring out a new edition. Foma got a half-hearted upgrade and then Moto had the RAZR - and they forgot that they made any other phones. Was a terrible shame. Through desperation and love of Symbian I bought an S60 phone, as UIQ was going nowhere. It's ok, better than average, but still nothing in comparison.
I think SE have since tried to revitalise UIQ with a 3rd edition, but the vast majority of the devout have given up now. What once was a thriving user community is now basically static pages.