Very disappointed with it as well. The combat is possibly the best combat in any TPS, imo, but the game overall was just boring. It made me appreciate Uncharted 3 more, to be quite honest. At least it still feels like Uncharted.
The great parts of Uncharted 4 are the best in the series, but they constitute like 30~40% of the game. Terrible, terrible pacing. They sacrificed gameplay to focus on the story, but frankly, it wasn't that good of a story.
The "treasure story" was amazing, but the character-driven part was kind of terrible. Sam sucks, Nadine sucks, Rafe was fun though. The characters we do love and wanted to see more of in the final installment don't get nearly as much screentime as they should (and those are the most fun parts of the game, imo), instead they decide to go more in depth with characters that, frankly, just aren't deep at all, nor they should be. Uncharted is pulpy action, they just react to the shit that goes down in a fun way. When Nate seems so bored while all of the amazing shit is going on, it kinda rubs onto the player, and I got a bit bored as well.
The exploration was also quite terrible, to me. They give you huge empty spaces with nothing. The meaningless collectible treasure was always like this, sure, but it took way less time to explore the environments in the previous games. Now there are tons of huge boxes of nothing. Way too little relevant side-content. The "lore notes" are interesting, but take some time to get interesting, and start to get better after the huge open parts, so even that doesn't help as much in those open areas. The Last of Us did it a lot better, because not only you had amazing optional dialogue and notes to look forward to, but exploration also directly tied into the gameplay because you were looking for materials to craft shit for combat and more exploration (like shivs). Here you get Sam making dumb jokes about piles of rocks, woohooo.
Again, the good parts are so damn good that it's hard for me to say that I don't like this game, but at the same time that I say it's a great game, I kind of hate it, you know?
The Last of Us is still my favorite ND game by a mile, btw, before someone tries to put my disappointment as a lack of capacity to appreciate slower paced and story-driven games, it's not only my favorite ND game, it was my GOTY 2013 and definitely one of the best games I've ever played. And it had a lot more combat than Uncharted 4, when you compare the pacing.
I didn't want to rank the series with only one playthrough of 4, but since I'm not sure I'll ever be able to endure another (again, did several with The Last of Us and can't wait for the next, since it's always used as a shield to what I consider to be design flaws in Uncharted 4), I guess I rank them as 1 ≥ 2 > 3 > 4. Golden Abyss was a mistake, it's nothing but trash.
EDIT: Completely disagree about the setpieces, though, I thought they were AWESOME, and very well paced. I only missed more "mini-setpieces" during combat. You know, those more creative encounters that Uncharted 2 excels at? We have one of them in Scotland, in our way to meet Sully, we have the elevator one, those are the kind of encounters that really make Uncharted 2's encounter design so brilliant, and I wish there were more of them. But the usual spectacle setpiece I was very happy with. Uncharted 3 had way too many of them, I found them perfect here.
And the multiplayer seems fun as hell, but I'm not paying for Plus, so when this free month I'm using now is over, that's it for me, unfortunately. The combat in this game is brilliant, and the multiplayer uses it to its full potential.
Still think I prefer The Last of Us' multiplayer, though.
I was telling people in the early spoiler thread that it's gonna disappoint alot of people because of its strong influences from TLOU.
Druckmann is inferior to Hennig when it comes to making an Uncharted game. Too much TLOU Kool Aid.
I really hope you're right, because that would mean Druckamnn isn't a one hit wonder, and as long as he doesn't try to do anything like Uncharted again, we can expect more masterpieces.