One boring game with three playable characters.
Playing as the marine you basically run and gun through the game. Playing as the alien you stick to the walls and attack with your claws. And playing as the predator you do a little of both.
This game has several flaws that range from frustrating poorly explained objectives to confusing instant deaths. Most of the mission objectives are boring fetch quests with the exception of the occasional find the switch room quest. There are a few boss battles scattered throughout the game depending on what character you are playing. There was only one boss battle in the entire game that had even the smallest amount of thought put into it and the rest were just the boring poorly designed run down the life meter battles.
Overall this game feels rushed. Rebellion needed to put more effort into crafting a separate unique storyline for each of the playable characters with different levels. And they also could have done more with the predator so it didn't feel like a mixture of the marine and the alien.