Dear Sailfishmen,
Now the first Jolla phone is 7 years old. Does anyone still have it in productive use? It still gets updates, which sounds nice, but can the old processor still do reasonably well modern web browsing? What about Openstreetmap? Does it perform well while navigating on the map?
I want to start with Sailfish OS, but on a low budget at first. Is old hardware an option? A couple of used Jolla 1 phones costed like 100 euros.
Forget about using the web browser for more than just some really basic pages, it doesn’t work well and it has a tendency to close all other applications because it runs out of memory. Otherwise, there’s really not much to complain about. I’ve been using the Jolla phone since January of 2014 and, other than the browser, the really, really poor/quiet loudspeaker and the battery sometimes running out faster than I expect (it still lasts several days on average, but I don’t use mobile data or wifi on it very often anymore), nothing really pushes me to get a newer device. Pure Maps, the best maps application you’ll ever find (it uses OSM maps), runs really well, too.
I don’t know your budget, but about a year ago I bought a second hand Sony XA2 for 110 Euro. Together with the paid version of Sailfish it was quite doable.
The Jolla 1 had served me well for 5 years. The software didn’t get slower during that time, but websites did get heavier. I would still be curious if a browser update (there is one coming it seems) would make things better again.
With regard to budget, I’ve seen Sony Xperia X for less than €100 several times over the past year (but you may have to add the cost for the Sailfish license to that). I switched from the Jolla 1 to the Xperia X about a year ago (I even paid only €50,- including license because the back was scratched and lightly dented, which does not concern me) and while I was reasonably happy with the Jolla 1, the difference with the Xperia X is very noticeable - performance, screen, speakers, wifi - all better, so personally, I would look around and try to find a good deal on a Sony, unless you can get the Jolla 1 very cheap. (Fun fact: my Jolla 1 died about a week after I bought the Sony - just won’t power up anymore…)
I still use a Jolla 1 (JP1301) as a daily driver. With every OS release, some functionality breaks and some gets restored or improved.
As already mentioned, it’s no joy using the stock browser with any modern website. Even worse, many just don’t work at all.
Organizer tools (contacts, calendar) gradually get improved by community efforts (mainly @dcaliste) and get more robust plus more features slowly over time. With SFOS 3, I’d consider this to be quite robust from my experience.
With SFOS 3.3 (Rokua), they broke the Mail app, unfortunately: the app blocks the UI for seconds to minutes and SFOS offers to wait or kill the App. To read e-mail on a SFOS phone, you need to be very patient.
The OS and the apps tend to use more memory with each release, and as has also been mentioned, 1 GB RAM is no longer enough for true multi-tasking these days especially if a browser is involved. On Rokua, there must be some memory leaks in messageserver5, too, so this aggravates things for people tending to have a phone uptime of weeks. So you have to be careful what apps you need to have running concurrently – it’s no fun when your navigation app dies because you start the messages app to read a text message.
The J1 along with the Jolla C are the only phones still relying on the bluez4 stack for BlueTooth. With Sailfish X models, you’ll probably get better connectivity and have more options like MPRIS.
I can’t comment on Android matters, because I don’t have Android Support installed.
All in all, I think that the J1 may be the phone with the best and most mature overall OS stability, which is quite impressive, given its age.
I don’t know what’s wrong with your phone, but Email works just fine on mine. You aren’t or weren’t using any patches to the Email application, right?
Bluetooth media keys work fine via MPRIS on my Jolla phone. What functionality is missing?
No patches to the Email app here, and I am honestly happy to hear that I may be the odd user with a broken Email app then!
Just one example: Sailfish 1 was able to send the track title to a Bluetooth audio sink. This functionality has been lost on bluez4 phones with Sailfish 2, regardless of the profile I use (or make it using). Just one example. TJC is full of on/off type reports of gadgets/functionality working/not working. I admit that my example is not MPRIS related.
I have 2 x Jolla1’s in use. Most of what needs to be said, has been already, so I won’t repeat any of it.
If you can pick one up for around €50, then its worth that just for the physical experience of what the device can/cannot offer you. If you don’t like it, sell it on. No need for mucking about with installing SailfishX (as per Sony devices), no license to purchase, just charge it up and use it. Whereas, looking at together.jolla.com these days, reveals the extremity of bugs/problems with running Saifish on a Sony device, I feel that SailfishOS on the Jolla1 is a little more polished and less problematic.
As for usage, well, I use it more as a playground, filling it with my own apps, mainly home automation stuff, whereas, I have no requirements for social media apps, just as well, the pickings for such native apps, is slim next to non-existent. Whatsapp works just fine and does not require any Playstore support, but does require the Android compatibility layer be installed from Jolla Store (built-in to device) allowing Whatsapp to run when the device is booted and to access to your contacts list.
Try one, you might like it, but if you want state-of-the-art hardware and a plethora of cool apps for just about anything, scroll on by.
If you choose to go with Android support, I would take an XA2. It gets AlienDalvik 8.1 and has good battery life. Xperia X is stuck on AD 4.4, Jolla 1 is stuck on AD 4.1. Xperia 10 has a poor battery life - and I am not the only one.
I still have a J1 here, just as a backup if anything goes south. 
WhatsApp would still be working, so that’s fine with me.
It’s a bit tedious, but it works. The main app-independent issue is the location service which is slow in the beginning, but works fine as soon as the phone found the location once (gathered the full atlas). For using something browser-based, there are already comments on that. For OSMAnd(+) - an Android app providing offline maps - the lack of performance makes usage a bit difficult and you have to wait sometimes after tipping on UI components, but in principle it still works.
P.S.: I also recommend you to buy a Sony Xperia XA2 or 10 (the former is cheaper).
Thank you very much for your comments! It looks like the Jolla 1 is overpriced in the category of old hardware, as it’s a rare name. On the other hand the market is flooded with better-performing Sony phones indeed.
However I’ve heard that on some of the newer phones, it is impossible to replace the battery. What an insult! This is the critical part that gets worn out on mobile devices, so it needs to be replaced sometimes! The old Jolla 1 looks good, as the battery can be replaced. What do you experience with the battery life of the aged phone?
CSD says my J1 battery is broken, having only 64% of its design capacity left. I still get a whole day of “usage” from it, where “usage” means phone calls, texting, being organized by the calendar, reading email and this forum occasionally and listening to audio books. I always switch off any radio I don’t use, though, and I have a spare battery.
I agree, but the battery of the XA2 can be replaced, however it needs much more time to do so than with the JP1. For example, here is a guide: https://www.youtube.com/watch?v=OL3QkIbWvRM
For many other modern smartphones, it is much harder than with the XA2.
What is “CSD”? Would you please point a link?
It feels like CSD has been with us for so long that I don’t remember how I learnt about it. I’ve found a link with some information that I seem to have forgotten already — I always start it via terminal.
You can also tap build version three times in Device info page under Settings.
Let me correct that …
Thanks @peterleinchen for correction, somehow I managed to test that so it seemed like three 
I also realized that TJC thread @Maus provided contains same info.
Just as a data point: here in the Netherlands (no idea where you are located), on tweakers.net, I just saw two Xperia 10s with Sailfish for €120 and €165…
Isn’t it another way to say that the hardware has become obsolete by today standards? 