Of the three SP4s that I purchased, one of the latest two I purchased, just stopped working. Battery fully charged, but just does not power up and it also did have I noticed, some speaker popping that it was not frequent. Now the other one of the two latest purchased while it is still working, I have decided I might as well return that one along with the one that has totally failed. I will stick with owning one of the par premium devices. And I do very much like the SP4 devices, but quality control just is not there. All have some light bleed, but as some have said not really noticeable but I figure better to only own one of these devices with acceptable amount of light bleed than 3. Hopefully by the time I try to buy another surface, SP5 will be out with much better quality control process.