I just bought one of these, albeit with slightly different specs.
A few annoyances:
In laptop mode, the screen portion is a bit heavy. Which means, if you lean it all the way back, it tends to tip backwards.
Also in laptop mode, the surface book will only go back about 15 degrees past 90. Not a huge deal, but might annoy some.
More worrisome is that when I got it in, it wouldn't turn on for a bit. I had to charge it for a while before it would turn on.
And finally, the detachment is not a simple tug. It's tied into the software, so the unit has to actually have some power to it before you can detach via the key. You hold it for a sec, and then it "unlocks" and lets you detach. If the power is too low to let the unlock function, you can detach manually via some (very) hidden mechanical releases.
As far as major problems, I haven't had any really. Works pretty well, and comes with the pen. I've enjoyed it so far. Speakers sound great, the thing gets plenty loud. It also gets very bright, though the auto-brightness adjustment is so sensitive that it will adjust based on its own light reflection in a dark room.