Many of these type of pills contain a few key minerals, amino acids and herbs. A usual mineral is zinc which is important for production of testosterone as well as semen production.
From a nutritional point, any man with a poor diet would notice a benefit from taking a supplement with zinc, copper, L-Argine and assorted herbs.
Many of these manufactures of PE pills would like you to believe that THEY have either an herb that no one else has, and/or a proprietary blend of ingredients that works the best...Don't you believe it.
If you look up the best, natural dietary sources of the above minerals, you will find that unless you eat whole eggs, certain nuts (DON'T SAY IT), seeds, shell fish, etc. - you will not get much zinc into your body.
If your interested in trying supplements, the internet can save you lots of money.
Just a warning: Minerals are not easily excreted from the body, so don't take too much and some of the herbs should not be taken on a continous basis (like more than 2 weeks).