sluggish? this has more direct feeling controls than a shitload of modern AAA games that put animation priority first and playability last, best example RDR2, which plays like absolute garbage.
play on double agent and see of it's still simplistic and boring. higher difficulties add more objectives and many levels have a bunch of intricate designs
floaty? it has a strong autoaim for sure, but the guns feel absolutely fine
it's an N64 game, and that doesn't influence the playability of the game at all.
except they aren't scripted whatsoever. enemies are placed at specific spawns each time you start a mission. they then either have a certain path they walk or a specific spot they guard. which is pretty much like most shooters work even today