Keanu Reeves' inability to act shows ...
... in every scene he's smoking in.
I certainly don't blame the dude for being a non-smoker, but when you're an actor playing a chain-smoker (and his habit being vital to the plot of your movie), looking like you only picked up the habit yesterday really doesn't help.
Every time he flicks his oversized Zippo or yanks the cigarette out of his mouth after taking a hit, he's just painful to watch. He looks like a 13-year old who just discovered smoking and is trying to impress his friends with (in his opinion) "cool" behavior.
Someone his age who has smoked since he was 15 simply wouldn't handle a lighter or a cigarette in this over-exaggerated manner. Look at real-life-smokers doing it on-screen and how subtle/second-nature their gestures are. Then watch Keanu doing his "look at me, everyone ... I'm smoking cigarettes!!"-routine.
S.