Privacy: you have less private space than in a house and typically share walls with your neighbors. Land: smaller lot size. Resale value: townhouses usually experience less capital growth than a house, roughly the same as an apartment.
Lawn maintenance isn't an issue. This is usually covered in your HOA fee. Be sure to check the HOA rules and regulations before you agree to anything. Some townhouses are detached houses, but as we've said, it depends on your area.