Some nice changes in this sequel. You have a few new moves, and the controls are tightened up a bit. Full stealth is encouraged more by the level design, the levels are more interesting, and it's a little more open-ended than the first game was (though still quite linear). There are fewer instances of the game forcing you into combat, and when it does happen it's less annoying, because the shooting mechanics are more forgiving than they were before. Each improvement is kind of subtle, but they amount to a noticeable difference, because they polished everything up and made it more intuitive, and as a result the game has aged better than the original too.
Apart from those changes, it's just more of the same gameplay with new levels, but I'm happy with that. Much like the first game though, it has problems on modern hardware, so check PCGamingWiki for fixes. I recommend disabling mouse acceleration through the ini file too.