There are two different apps now. The old one that you recognise gives you the New and Old Course challenges, and as you say, allows you complete control over if and when you want to repeat specific challenges. Both apps use exactly the same material, so you’ll end up reaching the same level whichever you use, but one approach may suit you better.
The good news if you’re finding the new app too inflexible is that the old app should still be available on the Samsung store – I re-downloaded it from the iPhone store only a week ago.
Like you, I don’t think the new app suits my learning style as well as the old one did, so I’m sticking with that. The downside is that you don’t get to see the text as you do with the new app, but for me, that’s a compromise worth making. There is no perfect method that will suit everybody, and other people will feel differently and be just as justified…
The new app uses something called Automagic, which isn’t split into discrete challenges, but provides the same material (all three levels) without any formal breaks. You simply stop when you’ve had enough and resume when you’re ready to start again. You’re right that the new app doesn’t allow you the flexibility to control your own progress the way the old one did; nor is it as suited for using while you do something else – I use the old app while walking the dog, and it was perfect for that. Automagic doesn’t respond to earphone commands so you can’t quickly pause when the dog runs off, then rewind a few seconds to get back to where you were.
Automagic seems to take this as invitation to repeat the current type of sentence much more often, when all you wanted to do was to listen to a sentence or two you missed. As far as I understand it, Automagic assumes that if you rewind, you’re finding the current topic as a whole too complicated and need to have that topic repeated more often, and of course, that’s often not the case. (This doesn’t seem to be explained anywhere, though, and it would be good to see more detailed explanation of what the algorithm takes into account.)
Having said that, the new Automagic app is very highly praised by many people as suiting their learning style better, and it’s obviously necessary for the ambitious plan SSiW have to extending into many other languages, so all power to them. I’m sure the current issues, particularly the inability to move directly to a specific point in the course, which is a deal-breaker for anyone who has made any progress at all on the old app, will be addressed soon.