I just finished Bioshock Infinite.
I really liked the gameplay, it was good, the shooting was decent and the powerup choices gave different ways to fight. I started at medium difficulty but i raised the difficulty to hard because the game was way too easy. I changed it back to normal in a couple of fights.
The thing is that while the story was good and the ending was really good there are lots of things that i did not understand, it looks really complex. Its one of those games that you need a second playthrough, quite rare i would say.
I definitely enjoyed it, its strong point its definitely the story and the narative but i dont get why people say the gameplay wasnt that good. Maybe because it wasnt open enough? Sure it could be better but it was very good imo.
Regarding the bolded
the Bioshock Infinite Spoiler Thread is quite detailed in making the connections between various events. One thing that must be stressed is that must of it had been written on "2nd April 2013", within a week following the game's release. As a result, the ending explanation portion in particular has now been rendered somewhat irrelevant given that the downloadable content (which I've not played actually) drastically alters things in a way that I have not yet been able to reconcile into a nice, logical explanation, but even still, when the main storyline is considered alone, the thread should be more than acceptable in connecting a variety of the aspects. It absolutely must be noted that I think looking at it as a puzzle to solve, rather than merely following it along passively, shifts the focus away from where the developers intended and despite myself having played a part in trying to deconstruct it in this manner, I don't think it adds very much to the game (even if some connections that Irrational made are quite clever).
Overall, I agree with your assessment in large, even if I don't find the narrative as strong/as big an appeal as you seem to, with a variety of threads which seem lackluster and mismatched. I believe the primary issue many find with the gameplay is the lack of depth present, the lack of need to use the entirety of the arsenal, the pacing preventing downtime, a rather bland selection of repetitive enemeis, the sparsity of the rails, and the hugely negative impact that the restricted level design places has upon the gameplay.
The lack of depth, and streamlining of the gameplay, is something which is particularly amplified when considering not only the previous "Bioshock" games, but System Shock 2 also. The eight vigors presented are quite interesting themselves, and the ability to combine them provides some additional variety, but don't capture the same level of variety and synergy found in the original's plasmids, either as a result of the huge salt burden (I forgot what it's called in Infinite) that certain vigors impose or the 'directness'/clearly offensive nature of all but "Return to Sender". "Charge", "Bucking Bronco", and "Return to Sender" were certainly the most interesting additions, but "Charge", somewhat ironically, falters due to the sheer effectiveness of it when combined with certain Gear and the upgrades, while "Return to Sender" had lots of potential but is acquired too late for much experimentation. "Enrage" (Posession is similar, I know, but I think the lack of vigors to direct it elsewhere subtract from it), "Security Bullseye", "Target Dummy", and "Telekenesis" were, in comparison, much more interesting powers with a greater mix of offensive-defensive strategies, and most importantly the EVE syringes being stored ensured that you could mix and match them at will, together without worrying about running out and sticking to cheaper ones. Given that you upgrade them with dollars (this is an important distinction), I would imagine that many players are likely to stick to one or two reliable ones ("Bucking Bronco", "Possession", and "Charge" are what I think would be most likely candidates) that have been improved rather than diversify, whereas in Bioshock and Bioshock 2 this wasn't too much of an issue (more so in the latter). The weapons themselves must be considered also, with the great reduction in weapon types (as a result of the ammunition-switching removal) and much more standard fare in terms of what's presented not being a particularly favourable aspect. This is compounded by the lack of a weapon wheel, which lessens one interest in experimenting further as why switch weapons if you already have something reliable and may not find it again?
The usage of dollars for the tonic upgrades ties into the lack of need to use the entirety of your arsenal that some may perceive as an issue (personally, I actually like it as you can tackle everything how you want). By having both vigors and weapon upgrades use dollars, you have to be much more selective about what you upgrade. While I, personally, always upgrade vigors, the carbine, and a second weapon (I forgot what as it's been awhile since I played it), I have read quite a few accounts from people that simply upgrade the weapons alone because they are effective, which they are. While I feel that the vigors are much more lethal in that they can handle a crowd and deal sizable damage while also having a defensive aspect, it is perfectly understandable that somebody would rather forego them given their reliance upon salt which cannot be stored. While not being able to store salt did help balance the gameplay slightly, it made power-use a much less appreciable option as one may worry if they'll manage to get more in time, simultaneously increasing the emphasis on guns and making you less likely to experiment with the available powers. I must, again, emphasise that I actually very much like this aspect, as I feel it allows for a greater amount of freedom in how you play the game, but this is an area that certainly could be complained about as people may not feel similarly.
While there is freedom in how you play the game, there is very little freedom in the level design, where you're constantly funneled down a rather narrow path at break-neck speed.once you pass the opening. The pace of the game, outside of one or two rare pauses, is relentless, while narrow corridors and sizeable yet rather empty open areas dominate the game, skyrails thrown in occasionally for good measure (which are completely broken by "Winter Shield", but that's more of a balance issue). I actually feel there is, in places, an interesting variety in the levels' openness but clearly there are those who do not, and it's perfectly understandable why. They don't really have the complexity featured in "System Shock 2" or even "Bioshock" and while it could be argued that this is not a fault with "Infinite" but is instead something derived from the players' perception/expectation, I think it's acceptable given the (deceptive, even if the original vision was completely unfeasible and the game entered a state of development hell) initial presentation/introduction of the game. The skyrails played a very minor role and only really covered a single area, or connected two, rather than spanning across multiple areas, reducing their impact. This is made somewhat more disappointing when the areas that featured them were some of the more dynamic combat arenas in the game. The enemies encountered were interesting, but at times it felt to me like there were too many simple foot soldiers and not enough variety in what you encoounter to make some of the combat scenarios more interesting. Make no mistake, the enemies were creative, unusual, and quite fun to fight against mostly (the Handymen a disappointing exception being extremely repetitive and monotonous to fight against, and a certain 'boss' near the end of the game being absolutely terribly designed imaginatively, and gameplay-wise), but it just felt like they could have made it somewhat more interesting by throwing in either a greater number of vigor-using enemies, or more 'special' enemy types.
One final complaint I've seen is that the enemies being bullet-sponges, without enough feedback to make the gameplay interesting. I don't mind this, but it is absolutely understandable as enemies require tens of bullets to be put down, particularly in combat difficult (to interject, I think this is what actually makes the vigors so good), and there is very little feedback that you're actually doing something to them. To use "The Last of Us" as an example, there's a clear visual feedback from the enemy as to what has actually happened to them after you do something to them, and it helps make the combat more satisfying. The large absence of this in "Infinite" may drastically reduce how satisfying somebody finds the gameplay.
Overall, I actually very much agree with your assessment despite enjoying the the narrative less interesting than you seem to, while there are also many other areas I find very impressive (the score, enemy and level design [not from a gameplay aspect obviously], the art direction, and), but these are some of the reasons I can think of that people may find the gameplay dissatisfactory, even if I disagree or am unbothered with much of it.