Advantages:
(1). You are correct, the shield is capable of defending against ninja tool, as long as they have not been infused with wind or lightning chakra. The wind chakra would allow the kunai to pierce through the shield whilst the lightning Kunai would pierce through it due to its elemental superiority to earth. Also they would crumble if hit with an explosive tag.
(2). Not only can it be used to halt or interfere with the opponents but they are also able to assist you in quick movements to evade incoming attacks, by creating a pillar underneath you on an angle you would be able to move your self away from the incoming technique.
(3). That is true, and even if you have ninja tools left, you will be able to create more if you ever need it
Disadvantages:
(1). I have to disagree with this one. Since it is a low rank technique you will be able to use it much more often then you would be able to use techniques of higher rank, as the chakra required is minimal and also it does not require hand seals.
(2). True but remember what I said able it being very useful in evading most techniques. I can tell you that quite alot of the more experienced RP's on this site use this technique...often. Me included.
(3).Same answer as the above and before

Used in different ways then it is intended is very useful and can save you most of the time. Remember that each technique, no matter the rank, has its uses. No technique is useless.
"Now, I want you to sit on the ground and concentrate on your chakra. I want you to focus your chakra into any part of your body that is connected to the ground and when you feel you have enough, release it into the ground underneath you and try to raise yourself up on a small pillar. Please be descriptive." Kirio looked at her student and waited.