I love it. Honestly it isn't my favorite Source mod, but I rank it above most, a must have mod for anyone with Source SDK.
I don't play much anymore though, but I love the amount of polish applied to it:
No crosshairs
Ironsight aiming
Everything remodeled - I think only the barrels are the only proof of it being a Source game
Feels like an entire engine remix
Cocking guns only when necessary
Way how sniper rifle ironsight aiming works
Nice gun library
Ability to switch fire rates (semi-auto, three-round burst, full auto)
My only problems with it are:
1. It's new beta basically ruined the skinning community
2. The M16-M203 and RPG-7 are overpowered
3. Not very populated
4. Lack of game modes
But as I said, a must-have.