izigame.me

This second installment is definitely way more demanding than the first, and that is its main justification for existing. Same bugs and quirks make a comeback, but, for the increased difficulty, they become that much more infuriating even in Normal mode, and especially so in the added Hard mode. Core mechanics remain largely unaltered, although some notable changes were introduced.
Gone is the fairly useless human shield mechanic. Combo rules became much more strict - only kills are counted but not knock-downs. Throwing items and indestructible, wildly swinging doors which knock enemies to the floor at the slightest touch are no longer all that much fun. Executions have to be timed to fit within the tight combo-window. These aspects are easily overlooked if you are playing slowly, for the experience, but become increasingly more annoying once you decide to go for A+ ranks on all levels because this requires a pretty much full combo on every floor of a level (chaining full combos between floors where possible will boost your scores even higher; just don't smash your peripherals in the process).
There is still no stealth to speak of - enemies have eyes on the back of their heads. They seem to have better eye-sight in this installment, with some positioned behind glass panels - frequently even off-screen, just often enough to be annoying - where they can still see and target the player. They can still shoot through each other, and do not let player's shots pass through them (with the exception of the ducking, firearm-immune enemies who insist on getting up close and personal in melee combat). In general, the second game features enemies immune to either melee or ranged weaponry much more frequently, while all but one of the playable characters can carry only one weapon at a time, having to throw it to pick up another.
The game reveals its puzzle component when a tanky, charging enemy notices the player and rushes forward ahead of all others, shielding them from fire; all while you might be sitting on a pile of weapons and frantically switching through melee (useless on the chargers) and empty ones to find a gun with any ammo still in it because the pick up mechanics were left unchanged. Weapons in a pile still get picked up in the order they were dropped in. Weapons dropped in or close to doorways might not even get picked up at all unless you are standing right on top of them. For a bit of added complexity, accidentally - or deliberately - throwing a gun away on Hard mode halves its remaining ammunition.
The level layouts are just convoluted enough to nudge insistently towards diligent memorisation of optimal routing when trying for higher ranks. There is an achievement for getting at least A+ on all levels in Normal mode. There is no such achievement for Hard mode, only one for its completion. No-one is stopping you from S-ranking Hard mode for fun - it even invites you to give it a go by featuring longer combo-windows! You would probably at least double or even triple your time spent in the game up to that point, potentially raising total playtime enough to rival a modern open-world release. That way you would also be snagging the dreaded, grindy 50,000 total kills achievement like it's no bother at all. Dare I say it, killer return on investment right there.
While the second game features support for user content, and - if the original did not exist - would be just about bearable for one play-through for those who enjoy piecing the fragmented, lacklustre story together, my recommendation to most people would be to just stick to the first game. Only consider the sequel if the original leaves you wanting more of a challenge. A challenge which will require enough time and dedication to learn the layouts on a clinically intimate level, along with an equally intimate relationship with Lady Luck.