In the end, free voiP can cause more problems than your landline. You might save a few dollars, but your ability to use the service may become difficult when your internet service is having problems. Since you can use the calling system from your computer, you need more security in order to keep your phone conversations from being hijacked. If this happens, your private conversations are available to others, who have no business knowing personal or company information. If this were the only problem then the answer to the question of whether or not free voiP is worth having would be yes. You can always provide enough security.
If you choose a provider that has dropped calls and is unavailable more than it is available, then it is not worth having free voiP service. You need to have the phone available at times if this becomes your primary source of communication. Is free voiP worth having also depends on the expense, the coverage area and if it is compatible to your life style. Your ability to forward calls to your cell phone intrigues most subscribers as well as the ability to talk from any computer as long as you have a microphone and speakers or a headset....