I decided to buy the i5/8/256/dGPU from Best Buy (they're local and the nearest MS Store is about 2.5 hours away). I looked at quite a few other laptops there a few days before, but the SB just kept calling in so many ways to me. Long story short, I walked in BB and they had one on a truck that was still being unloaded. Someone ordered it & then decided not to take it, so it was available to me. I bought it, the new Dock and a USB 3 hub I figured I would need. I have a SP3 set up in the SP3 Dock, but I knew the SB would require a little different setup on my desk.
Turned the SB on (this was Tuesday evening) but it didn't go through a setup sequence but to a sign-in screen! I've read a couple of other comments about the same thing happening to a few other forum posters. Anyway, couldn't log on so I contacted MS Chat. They led me through a reset, which went without incident. This was on a brand new spanking Surface Book. No idea how this could have happened. This SB was specifically ordered by someone for pickup at Best Buy, and I bought it as they were unloading it from the truck. Strange to say the least. After the reset, I did the setup sequence and let it download a few updates. It didn't hiccup during any of this.
Today's Thursday and I've been migrating software and data from my SP3...still am as a matter of fact (working it in with other responsibilities). Of course I've gotten on the web with it (Edge, Firefox), got OneDrive all set and other miscellaneous chores besides just transferring data and installing software. My point is that my SB hasn't so much as hesitated at anything. As I'm writing this from my SP3, I'm watching my SB download Win10 Pro version 1511, 10586. I've done all the other updates prior to this so we'll see what happens after today's update to Win10.
I'm impressed with my SB. I'm also thankful, so far, that it hasn't been a source of frustration. It just does what it does seemingly flawlessly and smoothly. For whatever reason, this SB hasn't yet exhibited one issue or problem. Like I said, something could come up later, but after two days, it's running like a champion racehorse.