I'm almost on only 12 days of switching to the
ecig from analogs. Yes, I now notice a huge difference in energy.
The first few days I felt different, almost buzzed from the nicotine. In fact, I felt more tired I think as a result. I was using the 24mg carts that came with my starter kit. I was also puffing away on the
ecig cuz I thought it was just such a cool
device.
I'd really recommend starting with much lower levels. Only enough to get you by. I smoked a pack to pack and a half of marlbro lights for a really long time, the 24 mg was too much for me to start with. I'd also recommend not using the ecig more than you would smoke normally. It's different as you don't really know when to stop using it.
Good luck.