Completed it on '99 mode yesterday, and disregarding the LOL worthy finale and overall plot, the game as a whole is a steaming pile of wasted ambition and compromised gameplay philosophies. Overall, the running theme with the game's gameplay design seems to be "lets take control out of the players hand, and do it for them -- because they aren't smart enough to handle that themselves!".
The gameplay as a whole is so fundamentally flawed I can't believe anyone can praise it at all, much less proclaim it as something better than its predecessor(s) in any way, shape, or form. The base gameplay is a really dumbed down and CoD-ified copy of BioShock 2, which takes all the flaws inherent in it and introduces a metric s***-ton more of them--all the while fixing none of the problems from before, and in the end you're left with a game with no real gameplay identity. Rather, what's left is a relatively poor mish-mash of CoD, Half-Life, and BioShock 2. Lets run down some of the changes and their problems:
Going full circle and removing essentially all the depth from the game that Bio1 somehow left unscathed from SS2, and totally destroyed the awesome gameplay that was found in Bio2. There is now 8 plasmids, a 2 weapon carry limit, no alt ammo, and effectively full regen health. Bio2's gameplay was balanced around keeping you out of cover by utilizing not only on-command-use medpacks, but also giving you several support tier plasmids and tonics to help recover your health and provide you with a strategically planned defense. BSI removes pretty much all of these, and replaces them with Elizabeth's tears (elizabtih spawning a decoy replaced the decoy plasmid, elizabith spawning flying turrets replaced the spawn turrets plasmid, etc.) which can only be used situationally rather than on command, like in Bio2. They also removed on-command med and mana packs, replacing them with elizabeth throwing you med packs or mana packs when she feels like it. Which frankly, both suck ass, and makes what was once a really fun and engaging combat system into a game of luck.. Other problems stem from them devaluing alternate gameplay builds entirely for a modern FPS style "everyone experiences everything exactly the same, or slightly different" philosophy. Pure melee builds are no longer viable at all, neither are pure support classes. Instead what's left are 6 physical and 2 support plasmids, all of which are essentially less precise, retooled versions of what was already there in Bio2. There are more issues like the shield system with no on-command med packs breaking the flow of combat and turning it into an elaborate game of hide-and-seek due to all the hitscan based enemies (like 90% of them, ugh....), removing hacking in place of pointless Elizabeth insertion, and the flat out broken checkpoint system, but those essentially either speak for themselves, or flow back into what I've already said.
"Mole's ass" aka Molasses movement speed is another thing. This a relatively minor and extremely annoying quip on its own, but added in with the rest of the crap (particularly, the new health system) it makes the gameplay rote and essentially turns the game into CoD with spells.
Overall, it's worse than Bio1 in pretty much every way. If Bio1 was a 7/10, I'd say this would be a 6.5 or so.
EDIT: Also what the fucking fuck is wrong with the checkpoint system?! I got three total in the last 9 hours of playtime, and two of those were virtually back to back. I lost 1 1/2 hours of playtime once due to a power outage and nearly snapped the disc in half