Gameplay I would say 95% similar to the demo version. Overall speed might be slower.
Usually I'll start Master League once OF for all league release by the community. So no comment on that yet.
PES 2017 is a much slower game pace and require much more tactical/strategy than Pes 2016. All issue related to Pes 2016 such as weak GK and Stupid Ref have been fixed.

But you may download the demo to judge yourself.

IMO there was a huge improvement from previous version, but it only can be identified once you play the demo, relying on the videos alone is not enough.
Last night I play in exhibition match using Liv vs Man U. After 4 defeat in top player dificulty, I start tinkering with the advance instruction. Using tiki taka and gegenpress.
My 1st game using this tacting was winning by 4-0.. I repeat a match using same tactic, and again winning by 4-1.

What I want to say is, you might need to change/ experiment the tactic by referring to available player, opposition tactic / formation and your own preferred playing style.
With the adaptive A.I. by the cpu, you need to attack / defend in various style of play. I.e. attack by using a winger from the start to the end of the game might not be a smart move to attack the A.I. this year.

And patient is the key to penetrate line defense.

Hope this helps

Ya after switch to Fifa 14,15,16 . This year switch back to we2017. I would say we/pes gameplay still the best compare to FIFA

the advance tactic could be stupid at times. e.g; when i use false no 9, during counter attack my striker just happily stay behind keep going back because of that tactic. T_T.
it's like the A.I dont know when to follow and when it's not.
thats why i don't activate it all the time.

and i notice playing champions league or uefa cup mode is harder than playing in career mode. O.o

playing online internet connection sucks, wat is the best speed to use ? need to update unifi i guess