[Galaxy Tab S Q&A, Help & Troubleshooting] ukael:
I love my Tab S 8.4, but I have two concerns about it:

- Screen homogeneity

- Performances

Let's start with screen homogeneity:

I exchanged the tablet several times and tested some more in stores. All of them were affected by screen homogeneity issues. I am being really touchy here, as it is only visible in specific situations: Extremely dark homogenous images that are not black, looked at in the darkness. The background used for TouchWiz settings for instance si affected: When looking at it in the darkness, I can see a gradiant from a dark deep blue to a lighter, green tinted blue. It looks quite good, but it's a deflect known as "mura effect".

Besides that, this is pretty much a non issue when looking at bright/mixed colors. The colors are vibrant, the contrast increadible, the blacks are black and the viewing angles are excellent. The counterpart is that the low quality of some textures become much more obvious with such a good screen.

Now, the performance part is more annoying:

Coming from a Note 8.0 and a Nexus 7 2013, I was hoping for much better performances on the Tab S 8.4. And I am disappointed.

The unit does to be swifter, but it's lacks smoothness. It could be related to the amount of pixels to display, to the lack of GFX power, to poor Exynos/Firmware optimization, to TW issue... but the result is a lack of perceived performances compared to my previous tablets.

Again, I am being touchy: I am used to perfectly smooth animations on 2013 tablets, and I notice stuttering and slower animations in general on this one. Here are some examples comparing Nexus 7 2013 to Tab S 8.4:

- Opening/Closing windows or apps animation: This one is 100% smooth on the N7, while often stuttering on S 8.4. At its best it can look smooth, but N7 will still look smoother. It also affects fading effects during loading times: In the playstore for instance, when loading a new page the fading effect tends to stutter.

On another hand, apps are loading slightly faster on Tab S 8.4.

- Games: I tested Riptide GP2 and Asphalt 8, and am now installing Fifa 14. Both game are running ok, but suffer from DPS drops. Riptide GP2 automatically goes for average settings, and still doesn't run as smooth as it does on my N7.

- Perfect Viewer (Comics reader) and Moon+ Reader (e-book reader): Two of my favourite apps, both of them are quite obviously running smoother on my N7 than on Tab S 8.4. By smoother, I mean scrolling pages with a higher FPS.

- Web browsing: No issue here, the pages are loading quickly (maybe even faster than on N7)

- Benchmarks: No issues here either. The Tab S 8.4 is a killer in benchmarks, with theorically a good 50% more performances than N7 2013. It looks like the power is there, and is optimized for benchmarks.

- TW scrolling: Extremely smooth, nothing to report here. Every launcher I tried ran smoothly when it comes to scrolling, but all are still affected with transitions during loading times.

As a bottomline, my feeling is mixed up. The power is obviously there, but it looks like only few apps are optimized for it. I hope to see improvement in future firmware, official or not.

Because even through these issues, this is an increadible piece of hardware. Difficilt to handle without a cover (it is too thin, and so are its borders), but well built, extremely slim and with an increadible display. It would definitely be an iPad killer if it was backed up by as much optimization efforts as Apple puts in its devices.