You are not alone in thinking the game is too easy. After beating the game for the first time, I decided to challenge myself in a different way.

I began a new game on hard, with the "Source Difficulty" Mod to make it a little harder, and the main thing is, I'm only using 1 source hunter to fight, I just left the other one in the city. Also, no leeching, stealth abuse nor rain stacking...

It's a lot more challenging, but even with all this, the game still is kinda easy. Sure, I have a lot of trouble against CC, but normally I don't have to do much to win.

If you can actually stand a chance with just one character, without cheesing fights, on hard, and with a mod making it harder, there's obviously something wrong with the game.