Non-existent to pitiful.

Applications are freezed when they are not active. This includes when screensaver goes on.

I guess many people have the expectation it would behave like desktop Ubuntu. But it doesn't. The people responsible for this part of behavior have time and again used the "iOS does it like this and look how successfull it is" excuse. Ubuntu Touch is looking at copying iOS in many aspects because they see it as successfull and what users want and need, and there doesn't seem to be much room for trying to do some of these things better.

I've watched UT development from the start and participated in it. And many parts of it (not all, mind you) makes me feel like they're just content on copying iOS on many important aspects - an open-source version of iOS to simplify it.

Despite my seemingly scathing words I'd like to still empathize that it is still open-source - much more than SailfishOS for example. So even though they have made choices that I strongly detest, you could modify even those parts if you were determined enough.

So I do nevertheless support Ubuntu Touch and wish them well, even though at it's current state I see little reason to use it myself.