I think the game suffers a number of major issues that mostly stem from Bioware taking a 'me too!' approach and attempting to implement everything they could without regard for how those features fit together in the overall design. This might have been passable if either the story or sidequests were really good, but both are bad.
For instance, there's the big one. The open world. Hey, Bethesda does it, we can too! Thing with open worlds is you have to fill them, and the developers obviously did not understand the enormity of that task because 95% of the game is worthless filler quests with nearly 0 narrative backing or anything of interest to note. The sad part is the open world doesn't wind up really getting used. All the main (see: semi-decent) quests are in separate, smaller zones. Then they decide to come up with mounts to get around this big world, but fail to implement absolutely anything which would make them worthwhile. They're not especially fast, your companions can't ride them, and there's no combat on them. Sad to see so much effort put into such a worthless feature. Or they have this idea to make you the next great power in the world, but still want to give you this feeling of traveling as part of a small, elite group. Those two concepts don't work. Either you're in charge of an army, who can accomplish all the menial tasks such as collection, scouting (actual scouting, as in providing real information, numbers, landmarks outside the immediate area) and who can actually apply aspects of their power...or you're a small adventuring band that's self-sufficient. The game does the latter yet treats you like the former. The result comes off as sloppy, and what aspects you can stretch your "power" on are petty by comparison. Sure, you can send someone off on a one-off war table collectathon of needed material, but the result after real time hours is less than a five minute walk in the woods. So it goes for all rewards in the game. It is far easier to craft better items than to be rewarded them, and the materials needed to craft them are easiest found on your own. So if the quests are uninteresting and the rewards are useless...why do them? The combat?
Oh yeah, the combat. Well let's start with some of the dumbest AI put into a AAA video game in the past decade. It's like the developers saw the praise for the tactics of the previous titles and said, "yeah, only less of that." AI has no concept of AoA and will not only rush through it, but actively stand in it. Ranged characters don't attempt to keep a range, but will actually move closer. The hold option is plain broken and will be ignored completely. Or how about the enemies, who far and wide contain few, if any, special abilities and are only capable of basic attacks. The game also contains most all the same issues of DA2's combat. You cannot interrupt an attack or spell once it has begun, only it's very noticeable now that combat isn't lightning fast. Wouldn't be such a problem except that enemies keep shuffling around, making combat this very clumsy battle of shuffling a couple inches and whiffing. NPCs will still drop out of nowhere in multiple waves rather than carefully designed encounters, only now they give the excuse of fade rifts and boss fights (both extremely common). Or, they want to take away dependence on mages by getting rid of healing, yet give them the ability to create essentially a second bar of health, thus establishing a dependence upon them.
I'd love to be a fly on the wall when this idea was passed, because it's just mind blowing to me. All this without mentioning the horrible, horrible PC controls they came up with. You have screwed up a tactical game if people who prefer keyboards are dropping them in favor of controller setups. When it comes down to it, the game doesn't play well. As a tactical game and an action game there are a wealth of titles which play much, much better, including the other titles in the series.
So yeah, why are we going on these filler quests again, if they're uninteresting, unrewarding, and lack even decent combat? Oh right, because we have to. You actually have to grind "power" to make main quests available.
What then about story and characters? Well, they're a mess. The plot starts of interesting enough, just sort of throwing you into the mix. But the pacing is awful, you'll be quick to discover. The game will contain a story-heavy sequence, then just sort of cast you adrift into this stale, open world with little ambient music for hours on end before another story sequence pops up and rushes you through another few plot points. Not a smooth design at all. The story itself is nothing to write home about. Some of the major events we were all hyped up for, the Orlesian war, the mages vs. templars, are total write-offs. The latter is barely even addressed to focus them upon other issues and the former is largely rumor mill and a formal party. Instead the plot focuses on...dun dun dun...an ancient evil recently awaken attempting godhood/to take over the world/to destroy the world. Yeah, kinda all three. A very incompetent evil as well. They lose all their momentum about a third of the way through the game and don't actually do anything else for the rest of it. And if you've gotten far enough to realize that, you've also gotten far enough to realize that interesting beginning makes no logical sense. There's a reason to sacrifice someone to create the most powerful artifact in the ever, and there's a reason to kill the Divine and halt the peace talks. There's no reason to risk the former while doing the latter. For all anyone knows, some random person might walk in and interrupt the sacrifi-ohw8. Or let's talk characters. The inquisitor is stale. No background, little personality. They are a chosen one good guy and nothing more. The antagonist isn't any better. All the history and lore they could explore with the character, all the motivations and tragedy we might be all be to glimpse. Nothing. Bad guy want be god, kill world, take it for self. Let's just avoid talking about the secondary villains. There's that one early on, in that one quest, who you might encounter if you happen to do that quest... Otherwise, they're total write-offs. Companions fare better, though aren't themselves especially great. They're actually kind of an unlikable bunch. A couple are flat out annoying, which is not something I recall happening much in other Bioware titles. But there's a few gems in there, so it's not all bad.
End result, a rather mediocre title. If I had to score the game it'd be a 2/5. It's just not good at anything which matters for anything. It's pretty and that's about it. The game is Kingdoms of Amalur all over again, only that game had fun combat and no fans to back the company no matter what trash they might throw out next. Inquisition is simply an unfocused mess with nobody looking at the big picture of what features would do to the overall experience.