Should you use Windows S?

TL:DR:
No.

Ok, after clearing that up, let's talk about what's Windows S and why it has a positive value (but maybe not for you).

Windows has been tied forever with back-compatibility, support for all the legacy apps and APIs that people have been using almost since Win95.

Every API is an additional support burden and a potential attack vector, and so we find that despite all the years, code review, tests and whatever, new bugs always popup.

So, is it really strange that Microsoft would like to close the attack surface as much as possible by allowing access only to a very limited API that removes low level calls and the ability to run any program that you get from any source?

Obviously they can't do it that for most of the people right now because most of the apps use the Win32 API and so the people at their homes would reject outright to even test that Windows if they know that it won't run some app that they use.

But on the other hand, there's a lot of people quite happy with their iPads and Chromebooks that doesn't run any Windows app at all and they boast how great they are because they don't get virus or malware there, and system administrators at school check the landscape and see one set of computers that are full Windows with all the extra maintenance that they might require and at the other side this restricted versions where everything is locked down, they control what's there and they know that the device won't run the traditional malware that it's sent in emails or injected through an evil ad.

They are the target of this Windows S, cheap computers that can be managed easily and can run any UWP or Win32 apps distributed through the Windows Store.

We know that most of the apps that people use aren't in the Store, but this might be the kind of incentive (a whole set of new computers sold to schools by the thousands) to port those apps to UWP and little by little people might found there more and more apps, and so in the future it might be possible for Microsoft to enable an optional lock down of every Windows computer so only approved apps are run there and everyone (except antivirus vendors) will be happy knowing that their computers are safer that way.

Microsoft currently has to fight an uphill battle to be relevant 5-10 years from now. Most of the people now browse mostly from their phones and tablets and they have lost this first battle to have a mobile OS that people use, and if they give up completely they might end up with a very marginal part of the whole OS.

So it really makes sense for them to do bold moves like this one and with the current set of existing frameworks to provide cross-platform solutions (Cordova, Electron, React Native, ...) then it wouldn't be surprising to find out that the ones that still aren't able to target UWP get proper support and everybody wins this way.