It's pretty fun. The only problem I have with it so far is that when you look down the sights of your gun, the sensitivity stays the same. In most games, when you look down the sights the sensitivity is automatically decreased because looking down the sights is used for accuracy and you aim more accurately with lower sensitivity, but people like to have high sensitivity when they want to run around so that they can turn easier when not trying to shoot someone. The fact that the sensitivity is the same regardless of whether or not you're aiming down sights really throws me off, and kind of causes me to just want to hipfire since aiming down sights don't really improve my aim all that much.
The rest of the game however is great. It looks gorgeous, and runs smoothly. I just kind of wish the beta had more than one map to play on, but at least the full game comes out in just a couple more weeks.