So, after using the Xperia 10 II with Sailfish for over 2 weeks now there's a few things that I've noticed that are a bit of a let down.

Firstly, despite all attempts Landscape just will not work, not even in native Sailfish apps even the camera will not switch to landscape.
There's a lot of Sailfish apps that no longer work, but I guess this is because they are in desperate need of updating more than anything.
Android support is still a bit cranky as in some apps don't start until you restart Android Support in settings.
I also notice that the screen gets stuck when pulling up the apps grid as in the grid will fully open but for about 3 seconds it won't scroll.
The camera is very unstable, always giving "Camera is not responding" for a few seconds, but I'm aware of some issues with Sailfish and the Sony camera.

Are these all being addressed in future updates?

Very strange how Sailfish works great for some ans so bad for others.
My impression about upgrades by reading much on FSO is that they bring solutions and bugfixes and also a certain amount of new bugs...
Did you search there for this device in particular to see if the same happens to other?

Sorry about your problems - on my XA2 it's been just working fine for a long time now.

Except the Camera, what are those issues you're aware of?

Also, what SFOS version are you on?
Some Android issues were ironed out in the latest update (4.3.0.12), at least for me.

And "There's a lot of Sailfish apps that no longer work" - I assume you mean Openrepos' apps, mostly? This statement would require more words.

It used to work fine on my Xperia X (until an update bombed it and I had to revert it back to Android

I've been ferckling about with it for a couple of days and have so far noticed that there's no "Dynamic" setting in the pully menu icon, it's either "Locked" or "Portrait". But if I set it to "Landscape" in the main settings the pully menu icon shows "Landscape" and apps like calendar will rotate, videos will play in landscape from the gallery but calculator goes all cranky. Android apps like VLC won't switch to landscape though.
The stock camera sometimes displays a "Camera is not responding" error for a few seconds after launch and even when it's brought back from the cover. I'm still experimenting with the landscape mode with this, but I do see the wallpaper rotate in the background when it's launched.

So, after tinkering about with this issue for some time I've managed to get some apps to go to landscape mode, Vivaldi and Fulguris browsers will, VLC now plays videos in landscape so does the stock media app. But now I can't get some of them to go back to portrait.