I own a Surface Pro 3, but it looks like you are interested in general feedback about the SP series, and the form factor.

Regarding the form factor, I'm very happy. Having had conventional laptops, I thought that the SP factor would limit the use cases; I can happily state that this is not true. It can be used it practically in every situation where you use a regular laptop, even sitting in the underground. Of course it's not exactly as comfortable as a laptop in those situations - so one needs to decide if he accepts "90% of ergonomy", or not; I do.

Regarding the Linux support, this is a thorny issue. I'm very annoyed for two reasons:

    1. some people will state that it works *perfectly* fine - it doesn't, and to think so it's delusional;
    with the SP3, you're stuck with a relatively old kernel (a 4.4.0.20 fork), without sleep functionality
    (it sleeps, but it keeps consuming power). Opinions like those are harmful, because they mislead
    purchase decisions.
    2. the hardware support (=patches) is having a really hard time to get upstream. Stock Ubuntu 17.04
    (4.10 kernel) has still issues (one major, I think wi-fi); the Manjaro officially supports it...
    except that it doesn't (primarily, the system freezes within 10/15 minutes, while using chrome/vlc, and
    possibly anything else). The only hope is the Fedora (which I didn't try).

All in all, if you're willing to accempt compromises (in the case of SP3, an old kernel, and no sleep support), it's a great machine.

I do use it very often, for professional development (and as recreational reader, booting Windows). The form factor, and the hardware, make it a very flexible machine, and the SP4 has even more hardware choice.

But be very skeptical of claims that it works perfectly, because it's factually not true.

edit: formatting, and cleaned up some concepts.