Microsoft are going in the advertising and search direction, instead of focusing on business and productivity that Microsoft used to be about. We've already seen some of the affects of that with Cortana and Bing Search being built-in at OS level, ads in apps, etc. and this is still early days, with forced updates they can push out whatever they want in the future.
I used to like Microsoft and their products because they were an engineering company with a strong lean towards business and productivity, not a sales and marketing company pretending to be a tech company so they can target consumers with the latest fad and cash in on their users data. With Microsoft being in the advertising and search business, it creates a conflict of interest because it's not just you who's their customer by paying for the Windows licence, but the advertising companies and various other agencies are as well. And with corporations being the greedy entities they are, monitoring, data collecting and tracking people in order to obtain greater advertising revenue would be inevitable.
Also, Microsoft are systematically replacing proper desktop software with low functionality, poorly thought out, screen-space wasting, mobile phone apps. With Windows 8.1 it's possible to just ignore all the 'apps' and carry on as normal, but with Windows 10 it's only a matter of time before all the legacy software disappears and we're just left with dumbed down apps. We've already seen it happen with Windows Photo Viewer, where a reg hack is needed to bring it back after a clean install. And we've already seen the effects of forced updates with the Windows 10 Mail App, where it isn't possible to go back to or keep using older versions of the app even if the latest version has functionality removed and you don't get on with the changes that have been implemented. Universal apps sounded like a nice idea, until the realisation sunk in that they would be dictatorship style apps created to accommodate for the lowest common denominator, which is a consumer mobile phone.
Subscription apps are likely to be the next thing to come to the Windows store, where you will be held ransom by your software. Keep paying up, or else it stops functioning properly. And if it's not subscriptions, you'll no doubt have to put up with distracting ads in your software instead, while all the time it hoovering up as much data about you as it can in order to sell on.
Windows is now facing an identity crisis. At a time where Microsoft are promoting the idea of 'One Windows', I think if ever there was a need to split Windows between consumer and business this is it. On one hand you have consumers where quite a few of them view their computer as merely a gadget/toy, the cheaper and trendier the better and don't consider functionality or privacy implications. On the other end you have people who are very much business orientated, consider Windows to be a tool, and strongly consider functionality and privacy implications. It's naive of Microsoft to assume people just use Windows to browse the web and keep up with whatever the latest app craze is.
All in all, for the time being Windows 10 doesn't offer me anything new that I want or need, other than it comes with a built-in PDF printer now. Most of the changes are things I don't want or need from a desktop PC. It's only my own interests I have in mind, Microsoft still get paid whether the licence I get is Windows 8.1 or Windows 10, especially if I end up going for a barebones PC with a retail version of Windows 8.1 Pro. But by going for Windows 8.1 I keep my options open for now. So that's what I mean by saying I want more time to assess just what direction Microsoft is going in.