Have you ever smoked a strong tobacco or cigar that has given you that tobacco poisoning feeling? It starts with a queasy feeling, and if you continue with taking a bite of something with sugar in it, you will eventually smoke yourself into nausea. But, if you take a bite of chocolate and continue, you will smoke yourself to sleep.
I have posted in about six threads since the format change, my own over-simplifications of what was posted by folks in the biology field that know more about blood sugars and how it is effected by nicotine. They are in this forum, and can be googled.
But, it is not a stimulant in the same way caffeine or other drugs are. It is linked to the release of sugars into the blood, and depletion.
Most people smoke pipes for the relaxing lowering of blood pressure effects it has on calming their nerves. Cigarette smokers don't get this effect from inhaling the more acidic nicotine directly into their lungs. They tend to get a more rapid heartbeat and nervousness after chain smoking several cigarettes. I've never gotten anything like this from the pipe... except for when I was first quitting cigarettes and moving to the pipe in the beginning... and I was slightly inhaling the smoke at that point. But, after developing better pipe smoking habits, I now only get relaxation.
Nicotine is an amazing drug, and the human body and brain is also amazing, with each person having his/her own reactions and experiences.