Killzone 2 is nothing like Halo, and Uncharted is even less like Gears.
Killzone 2 is weighted and tactical, while Halo 3 is more run and gun than even CoD4. Or rather, jump and gun. It's not a bad game, it's just different. Resistance is MORE like Halo, but they're still worlds apart.
Uncharted is a platformer-shooter, with some puzzles thrown in. Gears is a complete cover-centric TPS. Pretty much nothing in common. Quantum Theory is the only PS3 title which is similar to Gears.