In no particular order
Sounds not up to VST standards
Limited real time controls
Small touch Screen
Too much reliance on styles
Limited Midi
Limited control of additional keyboards and pedals
No capability to load 3rd party sounds
Nothing that will improve a players keyboard skills (The most important part of any keyboard)

Positives
Plenty of easy play features
Great for beginners and those that just wants to sit back play.
Plenty of song specific styles
Compact
Inbuilt speakers
However none of the positives have any relevance for me personally.

If you want Yamaha sounds for your computer just get Steinberg’s Halion Sonic VST, as since Yamaha bought Steinberg most of the new sounds were done by Yamaha.

Bill