I've been using Windows 10 since August. I was skeptical about it for some passive reviews about it. But Windows 10 is the trend, isn't it? I installed it and found it not that bad. It has improved a lot. The Task Manager is easier to find, you just right-click on the task bar, there you can find it. It's also easy to stop some programs from auto-starting up when Windows starts. The only thing that I'm not quite satisfied with is that the default text size is too small.
Yes you are right Windows 10 is the advanced OS compared to older versions of Microsoft's Builds. But I would like to say that some users feel that the older versions were good and stick to it.
The task manager was found even the older versions and the new thing implemented was from Windows 8 , i.e to opt the startup items, this feature was unavailable below Windows 8 OS's.
Coming to the default text size, Its depends on what resolution u are running in the monitor. You can change the text size manually to make it comfortable for your view by setting up in the Settings>>System>>Display window. i.e