Not really. They added a new assault rifle that required reloading (something only the pistols did before). They severely limited the amount of chaingun ammo to a few specific locations, totally gimping the weapon, they added one hit kill monsters for out of bounds areas, there was a lot more contact with off-sceen NPCs, the level design was a lot more detail (and annoying in places).
I liked the original game the best. Second Encounter next. Come to think of it,. they keep getting worse with each game… I still liked 3, but not nearly as much as the others.