They had a lot of the right ideas very early. They started building a high-resolution graphical mobile OS for 32-bit ARM in the mid-1990s, when most phones barely could display two lines of text and receive an SMS. Many concepts in iOS and Android today were pioneered by Symbian.
IMO, the biggest failing of Symbian was to disown the UI and focus on the lower layers of the operating system. Symbian's licensees like Nokia, Motorola and SonyEricsson wanted to control the GUI layer themselves, so they had annoyingly incompatible GUI libraries for Symbian. The platform was already hard to develop for, and then you had multiple vendors piling gunk on top like Nokia's Series 60 which was a terrible piece of work.
In a parellel universe Symbian would have acquired the BeOS team in 2003 and kept them in Silicon Valley, tasked with building a truly excellent mobile GUI on a five-year time horizon independent of Nokia's meddling. A well-designed high-level UI framework in a reasonable language could have made the embedded C++ underpinnings of Symbian mostly irrelevant — basically shipping Android a couple of years before the fact.
I know that they made stuff like the 9x00 communicators but they where never intended as mass market products.
Nokia was never able to craft a desirable product that brought applications to the mainstream user, most people who got their smartphones only used them as phones.
This is one of the things that I think modern techies have forgotten. No matter what you think of Apple, they were the only ones with enough market power to force carriers out of that position (Apple having been newly minted at the king of digital music) . It’s why the iPhone was exclusive to AT&T — because Verizon was the market leader and AT&T had to make the deal to get the iPhone. And Jobs wouldn’t make the deal with any carrier that insisted on adding crapware to the phone.
Symbian didn’t screw up the UI and it certainly was “too open”. It was so common to have malware and viruses on nokia phones. Bluetooth was scary.
The biggest issue of all was the incompatible app ecosystem. Each phone and OS and sometimes even models were different. Some were Java, others were Symbian and then the whole world of blackberries and windows.
Insert the usual disclaimer that Europe has a lot of countries with different legislation, but the carrier stranglehold was a US specific problem.
I never experienced that and don’t know anyone who did. Was it really a thing?
https://en.wikipedia.org/wiki/Cabir_(computer_worm) https://en.wikipedia.org/wiki/Commwarrior
NB tho, Symbian already knew (see 1998) how to make a "truly excellent mobile GUI" - sure, it was a PDA, but we were already making phone UIs with phone licensees then, and could happily have made a "well-designed high-level UI framework".
I'd've loved that "parallel universe".
Alas, the Symbian deal nixed it, and our new owners simply wanted us to make their kind of phone platforms for them: four whole new ones, in 18 months (heh right), mainly to their specs, while recruiting 100 new devs and 10 new designers.
So I feel it's a little harsh to say "the biggest failing of Symbian was to disown the UI" -- we never had the option to keep control of it. (It was a major failing of the Symbian deal itself, sure.)
https://www.youtube.com/watch?v=gqXTzlDZmhU https://www.youtube.com/watch?v=mjtKHPwTWsc
By then, Nokia had been working on a Linux based OS for years. (That would become Meego.) But, if I'm not mistaken, at least a thousand people were working on Symbian and Symbian based products. So switching away from it was simply out of question. It would have been too bold a move. (Especially, since Nokia was dominating the market and these products brought in a very nice profit.)
[1] https://www.alexanderjarvis.com/memo-nokia-ceo-stephen-elops...
The problem was that in the mid 2000s things were going just too good and management didn't want to see how it could become problematic, or at least take the risk. We were selling smart phones, that weren't really phones anymore (heck, we called them mobile terminals!) but it was pretty hard and painful to develop software for these. This made hard to convince external, indie/hobbist developers (they ended up creating most of the apps for ios and android) and, of course made internal development pretty expensive. Worse, it must have made experimenting and thus innovation slow. Hence the UI was stuck. Not as if Nokia ever put too much effort into innovating the UI. Touch screens were somewhat frowned upon. Though that may in part have related to the existing UI, the effort needed to try out something new and the fact that those touch screens were still resistive back then. Which is really not a great UX.
Though I remember once trying a prototype phone at an internal conference with a touch screen providing haptic feedback (through some piezo efect). So you could kind of feel the on-screen buttons.
The Symbian teams had finally managed to bring app developers along with platform improvements on Carbide, Qt integration, better POSIX support via PIPS, Symbian was finally looking more modern and then management dropped the bomb.
Naturally it was the last drop for many of those small app developers that had enough of the Symbian SDK changes from the last set of years, now being asked to drop C++ and Java, and rewrite everything into Silverlight/XNA for WP7.
Instead of adopting WP7, most decided it was time to go elsewhere.
Edit:
As you write they were expensive. So while Nokia was the undisputd leader in the segment for a couple of years the absolute numbers were not that big. I remember some year the worldwide phone market was 400 million a year. Nokia had over 100 million of them, but smart phones (Symbian) only single digit millions.
I like to look back and note some of the companies I helped in that little window of time I could contribute, but those contributions are long gone.
We don't build bridges in this business, thats for sure.
Software Manufacturing is a term that best captures my impression of the industry today.