They are a great choice, with several bundled together. Be sure they sink. Some won't. Anchor them in water 6-8 feet deep, standing up, if possible.
Here's the pros...they don't decompose, attract thousands of tiny baitfish into them, attracting game fish nearby. Plastic also tackles the task of being a medium for bacteria colony growth, which helps cleanse water and provides a bit of food for small fish.
Here's the cons...they attract small fish, not so much bigger fish. Lure's hang up easily, so artificial trees are tough to fish, except with soft plastics or weedless baits.

Teach a man to grow fish...
He can teach to catch fish...