A good comparison is the difference between The Raid and The Raid 2.
First one was concise and good for what it was, but the second had a greater emphasis on story which sometimes detracted a little bit from the action and at other times too much. The fight scenes were more inventive however, and the doldrums served to further enhance the visceral appeal of hand-to-hand combat.
Though I will say that I see both as equally good games. This one does turn up the violence, but I'd say that it's in line with the first game. Miami 1 explored the idea of violence in games: "do you like hurting other people?" and Miami 2 now goes further saying, "what kind of person does enjoy hurting other people?", with the story running the gamut of individuals who kill for profit, for politics, for misguided justice, for a 'greater calling' or for pleasure. I feel like the sexual violence scene in particular colours that first character in a similar way to Jacket: someone utterly deranged who enjoys causing suffering under the cling film disguise of "it's just a movie", effectively setting the stage for the rest of the plot.
Speaking as someone who also recently replayed the original game, I'd say that the mechanics have been changed to some extent, tweaked if you will. Combat feels heavier, especially when you have to aim, and it is more difficult than the original. The pace is sometimes more laborious, but it still allows for a sense of satisfaction, albeit a slightly different one to that of the first, which was closer to a quick adrenaline rush. I feel that a lot of the criticisms that say that the new masks are restrictive are a bit undeserving, as they are how the game continually challenges you without completely crippling you with swarms of enemies. They're more focal, and when you end up in that situation where you use a gun and a knife, you already come with the knowledge of which enemies can only be taken down from gunfire.
It smacks a little bit of picking apart the difficulty curve, since the levels themselves are designed around the abilities you are expected to have. When you, for instance, unlock the sniper rifle, the level becomes more spacious and hinges more on precision rather than timing. When you play as characters with the dodge roll, the game places you in unavoidable lines of fire so that you have to use the ability and not just have it as a tacked-on accessory like in the first game. I think that the masks are tighter here, whereas the first tended to broaden things a bit too much with its mask bonuses.
Overall, I found the game frustrating at times, to be sure, but it forced me instead to nut up and nail the rhythm instead of just giving up like the boss fights in the first game. Your character can sustain slightly more damage, and with the tweaks to the combat, there seems to be slightly more wiggle room in any given approach. The levels are well-balanced between a preferrence on twitch reflex and strategic foresight, but never leaning too heavily on one or the other. I will agree with the criticism that the way the game shifts between either end of the spectrum can be a bit tiresome, but that's more of a pacing and variety problem. The game drags on for a little bit towards the end, but the additional layers of paint on the story don't present themselves as unnecessary additions as much as ways to end the respective subplots.
In many ways, Hotline Miami 2 is like Pulp Fiction: an insight into another world with a selection of self-contained stories sustained by ultra violence, all of which end at least a little bit strangely, but in a way that is in accordance with the deranged universe in which they took place.