My early childhood was during the beggining of the Android/iOS era. Here in Poland there still were a lot of people using dumb phones or feature phones, but in short time everyone between 7 and 50 years old got an Android (or iPhone if someone wanted to pay a lot of money for a phone). First cell phone I owned was an old samsung, not sure if it has Java, but I didn't know how to install my own programs anyway. Then some time later I had bought my first, very budget, Android KitKat phone. These times I even didn't know about Symbian's existence, so it's not strange that I've never used it.
Until recently, when I got this nearly brand new Nokia E52 with S60 3rd Edition system. As far as I know it's just Symbian with Nokia things.
What does it can
So, out of the box we get all the features a phone in 2010 should have and more: calendar, web browser with web acces through 3G and WLAN(!), FM and Internet radio player, music player, video player, 3.2MPix camera (photo by me), dictionary, email client, maps, voice assistant, Facebook, Youtube and other software (I'm not sure if was factory installed) to name the most notable ones. Of course, not all of them work today. There was also an Ovi Store where you could get apps, themes, music and maybe some other things. It's also not working today. But you can just install apps from .sis files, right? Well, it's not that easy (but still easy).
Hacking
To increase security apps installed on S60 had to be signed with special certificate. Even if you want to install an app which has proper cert, it's already expired, so it won't work with current date set on the phone (and never with SIM card inserted, I guess). So, to not be limited to Java MIDlets you have to do a little bit of hacking.
I won't explain the hack in detail, as you just have to follow instructions found on some forum and use right tools. In my case I installed Norton Security and some hack from the same file (had to set date to 2011 or something like that) then did some time changing magic and restart so Norton didn't complain it's not activated or something like that. When finally got Norton to work I had to restore some entries from quarantine and uninstall Norton. Then I installed ROMPatcher+ and enabled some patches. The instructions also said to install something called InstallServers but I haven't got it to work and everything's right (but maybe things that didn't work didn't work because of that).
The phone is finally hacked, it was easier than i thought it may be, so I finally can install some software.
Web browsing
To be fair, I haven't tested wide variety of software kinds, instead focused on things which interested me the most - web browsing and games. For the first one, there is a preinstalled web browser called Internet. As I've already mentioned, you can gain acces to the Internet in two ways - through cellular network or connecting to WLAN in 802.11b/g standard. I've choosen the second method and connected to a hotspot from my smartphone - E52 doesn't support WPA2, at least with my software version. I managed to connect to HTTP websites, but the browser didn't cope with modern HTTPS.
Opera Mini entered the chat
To install opera mini you open the built-in browser and google for "opera mini symbian" or something like that. Not on the first position, but somewhere on the first page there will be a site you can actually enter - this one will detect your phone's model and you just click the link which downloads the installer file, it installs automatically after downloading and you can start browsing the entire web! Well, term "entire web" may be a little exaggerated, but all websites I've tested loaded and were usually kind of usable. I had no problem with my website. On YouTube I could browse videos, but it was impossible to play anything. I've been the most disappointed with Melon's website, which is based on frames. I could browse it, but only within the area the frames were fitting the screen (it was just impossible to scroll the frames). But still, websites are loading fast and modern HTTPS works.
It's thanks to the way Opera Mini actually works. Instead of just loading the page from the Internet as it is, the URL entered in the address bar is send to Opera's server where the website is optimized for phones and compressed and then sent to the user. It's quite amazing that you can load nearly every website, even on older phones (Opera Mini is also for Java ME). You can achieve simillar effect on any browser in your local network by setting up a retro proxy server, which is meant for vintage browsers. Haven't tested it though.
There were also clients for Facebook and Youtube preinstalled. I haven't tested the Facebook, and the YouTube doesn't work (also in browser). There's a new YouTube client for Java ME but it haven't worked for me. Maybe it would work if I used cellular data instead of WLAN.
Can it run Doom?
It depends of what do you expect. I managed to run DoomRPG, which was quite popular game for Java. If you don't accept it and want the original Doom - it's possible, though when installing C2Doom my phone said it's not compatible with it, so I gave up.
Speaking of games, I'd like to say a few words about emulators. For me, the best thing about Java phones today is that they're able to play Game Boy Color games using MeBoy emulator. I'm currently playing Pokémon Gold on it and I like it more than playing on a 6+ inch Android smartphone. To set it up, you just download MeBoyBuilder.jar, select roms you want to include and click create MeBoy.jar. Then you just install it on your phone and you are ready to play. It's Java MIDlet, not Symbian app, so it likely will work on some phone you have somewhere in a drawer and no hacking is required.
It's even possible to play Game Boy Advance games, using vBag emulator. Of course, there is also a lot of games dedicated for Java or Symbian. I haven't tested them yet, but I have titles such as Townsmen, Galaxy on Fire, Assasin's Creed or Asphalt in mind. (I actually played the last one before).
Some thoughts
I don't like the way smartphones have evolved. A phone fitting in your pocket? There's Apple, but the iPhone 14 won't have the Mini version already. Battery life? It lasts for a day of using, with giant 5000mAh battery. (Remember phones which lasted for over a week on one charging?) Physical keyboard? Only in some expensive community projects. Instead you get super-duper 420MPix quadriple cameras which stick out from the housing and high performance to run poorly optimized apps with visual effects no one asked for. What was your phone 5 years ago? Compare it's performance to your today's phone. And now think what you can do, do better or do faster thanks to this performance increase. For me, not many things changed. Maybe I'm just tedious. Judge for yourself.