Very poor. Not what we were all expecting.
If Yamaha did this because of the Korg releases last year fro the PA700 and PA1000, it is clear. Korg released two keyboards that have very good specifications (except for the sampling memory). The bad side of Korg was that they made this big release, but without having the keyboards in stores to be bought... But the difference between Korg and Yamaha is that Korg really made an upgrade from their last models. It felt like a big step forward.
On the other side, Yamaha lets the users to feel like in the other industries, where a button is changed from one side to another and a little bit more memory and 2 mega-pixels in plus and: new product. These are not new products, but marketing move (and not very clever).
Why not clever? Because the Korg users will not pass from their keyboards to Yamaha (specifications are less). Only difference is the sampling memory (but Korg can make it more with just Operating System updates).
Also, current Yamaha users will not pass from S770 or S970 to the new models (there is no reason: the sampling memory it's on not such a big difference that you would sell your old keyboard with less and buy almost the same with more).
And somebody said that old keyboard users will think about getting these new S775 and S975. I think not. Why? Because everybody was waiting for a touch screen with a better User Interface than Genos. Korg is with light years in front in this matter. Because everybody was waiting for more memory and better handling of audio files. As long as you have 13 MB of internal memory, and Korg has 0,90 GB = 900 MB what upgrade would you think that old keyboard users will take?
13 MB for internal memory, without having at least two USB ports, is nothing. In 2018 we should not talk in Mega Bytes. But this is an old problem of Yamaha. Yamaha, I don't want to carry everytime a USB stick (that I can lose). What I use, I want to have in the internal memory (and we are living in 2018, when Flash memories are not a fortune). Also, I don't want to use an USB hub.
Mono legato is a must in any normal arranger with sampling. This is not an upgrade. This is software and could be done in previous keyboards.
Half bar fill-in...
I just hope that there will be major improvements in Yamaha Expansion Manager: and we will be able to use the internal voices with our samples to create new voices (which Korg has for years now). I hope that in Yamaha Expansion Manager we will be able to import more types of files and even the protected ones from previous models (because there is no use of a Customs User tone that you cannot change; if you cannot change it at the level of sample, than your YEM is just a marketing tool and it helps only the ones that want to sell).
Add in YEM possibility to copy/paste voices to elements (so that you don't re-do the note-by-note again and again when you what to combine certain tones).
Add a possibility to make and hear the voices in your keyboard (without making them on PC and then going to keyboards and loading; afterwards realizing that you need to change something because it doesn't sound right and go back to PC and modify without hearing again; going on a loop).
Add possibility in YEM to change the tones in the styles directly in YEM (without going to keyboard, in the simple Style Creator, making change and going back to PC to add them in the pack to have them in the internal memory).
I hope that there is plan for a new Style Creator with advanced features and possibility of real making of styles and customizing. The current old one is a little behind (user interface, possibilities etc.).
Also, the software used with the external devices: update your policy and put software for Android users also (and specify the compatibility with certain tablets, phones) and you will have a big success. You don't have a touch screen, yes? OK. Let the players use their tablets to access the internal voices, features,: the same screen you see on the keyboard (not the screen from Genos) and with touch features, all controlled through MIDI-USB or Wireless. This for sure can be done (and you have to invest only in software without making changes to the production line).
Yamaha could put Korg on their knees with just some small moves in hardware and software.
I could write for days here, but nobody listens anyway, so I have to say that I am disappointed in Yamaha. I am an Yamaha user. But I am thinking of getting a Korg for my next keyboard that I buy (and keep also an Yamaha).
Look at below presentation. The new things in these new PSR S keyboards are only on 1 page, on 1/4 of that page and you can number the words on your fingers.
https://youtu.be/BBq_SaXSUCUWe waited for much, much more from you Yamaha...