Action Half Life 2 is designed to simulate the experience of being in an Action movie. Movies like Hard Boiled, Face Off, and Die Hard are the inspiration for AHL. AHL2 is AHL reborn on Source engine.
If you liked AHL (either HL or Quake) then you should also like AHL2. Fun mod to play. Only minus points for the notorious crashes and map bugs which for some reason got ported over from AHL. Otherwise you should not miss this if you liked the original AHL.