There is a lot of bad rep that all snails have received. A lot of hobbyists tend to think that having any type of snail in their aquarium is horrible and all must be removed immediately. There are even chemicals that are solely meant for killing snails in the aquarium. I highly recommend that you never use any chemical meant to kill snails in a tank with shrimp. Snails are not bad for your aquarium. Overfeeding your tank is what causes snail outbreaks. Most snails will actually leave your plants alone and instead eat the algae off of the leaves as well as glass. Do not think that a snail is a pest, they can be extremely useful in any aquarium.
The Malaysian Trumpet Snail is actually a benefit to any aquarium for several reasons. It will not eat your plants at all. This snail also will not "muscle" your shrimp off of food meant for the shrimp. The Malaysian Trumpet Snail feeds on detritus and leftover food that is underneath the substrate. It actually burrows in the substrate and moves around throughout. You will rarely see this snail during the day. Occasionally it will emerge from the substrate. A cool thing is that sometimes you will see the substrate move and you will know that there is a Malaysian Trumpet Snail underneath doing its cleaning duties.
http://www.planetinverts.com/malaysian_trumpet_snail.html