Do you mean the emotional feelings or the feeling of having someone cum in your mouth? I'll answer the second question first: With his cock in your mouth if you slide the tip of your tongue into the slit you might be rewarded with a droplet of pre-cum. It has a slick texture like olive oil but usually no taste. When he is ready to cum you'll usually know. Make sure to let him know before hand that you want him to cum in your mouth. Now there are 2 ways you can take his load in your mouth:
First, you can take his cock deep into your mouth (to the beginning of your throat) so that when he cums it basically goes directly down your throat. Only drawback is that you might experience a gag reflex depending on how strong his ejaculation is.
The second way is to have the head of his cock in your mouth when he cums. In this way the sperm will pool in your mouth until you swallow it down. If he cums a lot you may have to take it in more than one swallow. Cum varies from guy to guy, some is thicker and some more watery. The taste? Hard to describe; somewhat "chemically", a little salty and a little bitter. Again, it varies from guy to guy depending on their diet and whether they smoke. If you've ever smelled cum, even your own, it basically tastes like it smells. As a test (as it may be difficult) try your own.
Finally, when he cums try to cup his balls in your hand if you can. It's quite the sensation to feel his PC muscle contract and his balls constrict as the sperm is transferred from his body to yours.
As for the emotional aspect, swallowing a man's cum for many is very spiritual; you are taking his essence into your body, and like anything else that goes into your stomach, it is broken down and absorbed. It is a way that one man can nourish another and actually become part of that person. A man's sperm is something precious and unique to that person and him offering it to you is an incredible gift. A personal pet peeve of mine is when a guys cums in someone's mouth and they spit it out like it's poison.
Have fun and enjoy!