I don't know about energy (I feel like you must be right about that), but when I made research on smoking for school, I remember that pretty much all of the positive feelings were (according to what research suggested) just the attenuation of the effects it created in the first place.

I also remember that those negative effects could last very long to the point an ex smoker could feel some of them for weeks, even longer if we count psychological effects and not just physical. Haven't brushed up on the topic on at least a decade so I could be wrong, but I'm biased towards it being the most heinous thing because I really hate smoking.