I have a SP4. I don't care what it is called. It is a device that, by design, requires at least a mouse or digital pen. In other words, it could not be used to the full extent with only touch input.
I use it plenty as a tablet without external mouse and keyboard and even for some productivity since it has a full on-screen keyboard option with control, alternate, function and windows keys which is non-existent or rare on ARM tablets.