Half life source adds ragdolls, new water effects and bloom to half life but takes the fun from series.
The original half life is fun because of it's mods, let me name few: Afraid of monsters DC, they hunger trilogy, point of view, scientist slaugtherhouse, species like us, Heart of evil etc. None of these mods are playable on the source what adds too little replay value to game.
The graphics on half life 1 were good because it was released in 1998, but source was released 2004, what the hell.
Half life 1 is an shooter where you play as scientist who works in black mesa named: Gordon freeman, who arrived late to his experiment, experiment however get's blown to pieces, making connection with a world named XEN and everything goes to hell.
As you fight towards escaping the black mesa, HECU marines are sent to take care of the facility and murder everyone they see.
Source is good when you haven't played half life 1, but if you have played half life 1, enjoyed mods. It's just too weak.