Short note on what I have found to be the most useful way of using MS Surface Pro 4 in my daily workflow: firstly, I have mostly learned to ignore the dedicated “Windows 10 app” versions of services that I am using. The user experience in those, stripped down versions are generally rather bad. It is much better idea to use the full, desktop version (if available – and Surface Pro 4 is powerful enough to run the desktop one in 99 % of cases). The second option is to try using the “web app” version of the service – even those are generally much better than the “app” you might find from the Windows Store. Chrome is really helpful here, as you can save almost any web page into a Web App to the Windows desktop (go to: Settings [three dots up right], then ‘More Tools’, then ‘Add to Desktop’). The web versions are versatile and powerful these days, and you can e.g. easily enlarge elements in the web interface by simple ‘pinch zoom’ finger gestures – in contrary to the Windows apps, whose interfaces mostly do not scale at all.
I have also tried to learn my own user interface technique, which is a combination of scrolling and pinching with my fingers, precise pointing, underlining, drawing and writing with the Surface Pen, and more exact mouse work, where I currently mostly use Logitech M570 Wireless Trackball. I have never really learned to enjoy the official Type Cover, even while it is great improvement over previous generations of thin-and-light keyboard covers (there is still bit too much flex, and the shallow and imprecise key movement sometimes really irritates a touch typist). So I use a high quality external wireless keyboard, currently either a Logitech K810 or a K811, which I have several.
The downside of this system is that there is a real patchwork to move around and set up: Surface tablet, Pen, trackball mouse, external keyboard, plus of course the power brick. When contrasted to a regular laptop, the benefits are in flexibility: in tablet mode, I can go some time without any other items, or just work with the Surface and the Surface Pen (e.g. when marking drafts and grading student work). But when writing and productivity tasks take priority, then a regular laptop would indeed make things a bit simpler. Maybe the next version of Surface Book might bring these things together? Currently there are some nice compromise efforts (e.g. Lenovo Yoga 900S), but there are multiple compromises in e.g. processing power, storage, pen integration and keyboard quality that this kind of “convertible ultrabooks” take, as contrasted to having separate devices that are all excellent in what they do.
Thus, my current patchwork seems to work best, for me, at least.