Many points were raised but I would like to address the gameplay changes from origins to inquisition.
1. Gear is locked to certain classes in inquisition.
2. crafting > inquisition is broken due to crafting. craft the most simple gear and it will be 10 times better then anything you can find.
3. healing was removed, in inquisition you can't heal with magic only with health potions which are limited. this hurts the flow of the game at the start but then you reach skyhold and get fade-touched silverite and game over.
4. in origins we had splendid tactical system. I could "program" each companion to do exactly what I wanted in the moment I wanted. In fact once I've set up my companions I didn't need any tactical cameras or anything they butchered everything easily.
In inquisition at the start you need to control all of your companions but then you get crafted gear and you don't need to bother.
5. while indeed in origins you had broken builds like master race BM\AW build in inquisition it's just... sad. Sera.... she can solo anything one nightmare using her flasks... or blackwall which can't die... c'mon...
6. the companions themselves in origins were also nicer imho because they weren't locked into specified build. they had base class and 1 advanced class. you could give them whichever build you wanted and whichever advanced class you wanted. in Inquisition due to the game mechanics of no heals and only damage mitigation combined with the lock(rogue) \ Barrier (mage) \ Walls (warrior) I had to mix each time 1 of each class and respec all my rogues as range dps, all my mages as spirit support and all my warriors as S&S tanks.
otherwise I could not use some of my companions due to needed classes to clear paths or the need for support and tanks.
7. Another change gameplay wise worth note is the crafting system in origins was much nicer. you had stores selling unlimited supplies and didn't need to fiddle with respawning mats to collect all over the place, much more simple and intuitive.
8. Also gameplay wise the maps on Origins were much better imho for this type of game. they take the classic single player approach where a map is static and nothing in it will respawn once you cleared it. the fact inquisition got mmo style open world just hinder the gameplay for no reason.
I would also like to address the execution of some mission in bioware games to show the difference,
1. NWN: HOTU - > Chapter 2. you are in the drow rebel city, you destroyed the allies of the valsharess and gained allies of your own. then there is a siege at the gates... according to how you prepared yourself then the battle with execute with multiple phases and interesting mechanics..... lots of fun!
2. DA:O > Gates of denerim. first we get speech with cutscene. then all of our companions joined by the leaders of our alliance zerg the gates and fight with you to capture it! glorious!
It continues with our team capturing each part of the city, saving people and destroying the darkspawn forces, bouncing back to the gates to do the "battle" our companions which were left behind are fighting. again it was made very well and lots of fun.
3. DA:I > Siege of the adamant. we got cutscene... looks promising. then small scale battles to "clear" the ladders... which is underwhelming... where are all our mighty black templars charging up the ladders? nothing. then we get to courtyard with 1 demon to fight.... then fade. bah... what kind of underwhelming execution of mass battle this is?
If I'm allowed to sin and compare this to another game which was not 100% made by bioware but still relevant it's NWN2,
you prepare your fortress of crossroad keep, in a long and in depth mechanic to raise mighty fortress and protect the land while building your forces to stand against the king of shadows.
then when hell break lose and the fortress is assaulted you got number of phases... from defending the wall and destroying the siege towers to holding the gates with your companions and holding out until dawn arrives to drive away the shadows... it's masterpiece of siege battle missions.
Again I must sin....
NWN2: Mask of the Betrayer
final act > siege on the wall of the faithless
no words needs to be said.. you are assaulting the heavens with hosts of mighty legendary beings... each part of that mission is beautifully made.
Mechanics, gameplay and execution of quest chains in Inquisition are step down in my opinion.