I absolutely love the charm bar. It is elegant and convenient to use in tablet mode. But then having separate app settings (swipe down or up from the bottom corners and from the app's own charm bar) might be confusing to some people. Anyway, it took me 1 minute to get used to it but I don't know about others. And also, it's meaningless in desktop mode. I think what MS needs to do is to decide which features are good for each mode, then separate them by making them only functional for the respective mode (for instance: charmbar for tablet, taskbar for desktop), while still provide a smooth and seamless way to switch between the two modes.
I think the problem with MS is that the designers are trying so hard to unify the user experience on every Windows device out there, hence the taskbar in tablet mode, which I think is ugly and does not provide any mandatory function other than a place to harbour Cortana. Like someone mentioned before, an always visible taskbar in tablet mode takes up the screen's real estate and distracts people from contents. Just because on a Windows phone, we have three buttons which are back, windows and search (Cortana) doesn't mean on a Windows tablet, we have to have the same thing. They are different devices and used in different scenarios. That's why a phone is called a phone and a tablet is called a tablet. Providing a seamless experience between devices, imho, is to make them work well together not make every single thing of them akin. They seem to be trying hard to imitate Apple, thinking that because an iPad and iPhone have the same OS, function in the same way, they have to do it too. But really, what make Apple's user experience deceptively great is that their devices work excellently with each other within the eco-system.
P/s: It's a bit sad for me to see that even in Windows 8.1, which is a legible MS operating system, the word Cortana is recognised as a spelling mistake.