Aside from feeding others in the food chain, garden snails do serve a purpose. They help promote the natural decay of a garden and feast not only on the healthy plants but, help to rid the garden of sickly plants. All of which, come back to help nurture the garden and chain of life. Although, I do take steps in order to eliminate mosquitoes, spiders in the home & ants; I am officially re-thinking the fate of these cute little shell bound creatures. Believe me, I even put out "pet friendly" snail poison... Kills the snail but, not anything else. In fact; on a really humid night, the snails came out in army force and headed straight for my lavender... Instead of killing them, I relocated them... At least 40 + we transported from my garden that night!! Well, that's not the end of it... Recently, I was tossing snails from my patio and accidentally slammed the back of my hand against the tree and, the little snail in my hand went "crunch." Being that I have been going through some pretty bad luck, I didn't want anymore bad karma... Although I may be nuts, I went on a mission to save the snail. Twelve days later, she or he is doing fine. I kept it from other hungry creatures, fed it and used clear band-aid to help mold its smashed shell together. The snail is snuggled safe in a clear plastic container... After going on-line, I mist it in order to keep it from dehydrating, and provided it with plenty of leaves, rocks etc to crawl on. The little snail wasn't too interested in the leaves but loves apple, carrot, bean sprouts and cabbage. I even bought a calcium bone to help strengthen its shell and will soon set it free back into my garden. Yes, an odd story I am sure... However; my conscience feels better and I honestly, can't imagine smashing these cute little guys on purpose... We are bigger than them and there has to be an alternative...
I suppose they thin out plants in the garden so the remaining plants are healthier. You can learn more about snail ecology with this page.
They provide food for birds, and thats about it.
No these garden snails are not good for your garden and they destroy leaves by eating them and especially fruits so you must get rid of them if you have beautiful garden and you want it ever green.