The problem with this discussion is that there is a difference between someone "playing" FSX randomly on their home computer on the one hand, and using FSX under the guidance of an instructor on the other.
They key to getting any benefit from one of these simulators is using it as a part of a larger curriculum, only for specific learning objectives, only as a supplement, and finally only as directed by a real instructor. Even the FAA link offered by Phillip states "The FAA recommends that instructors use an ATD in an integrated training curriculum because of the benefits that training curriculum provides." Techwing likewise stated, "When used as part of a complete training program..." But home users typically do not have the needed instruction, do not approach simulation in a deliberte and methodical way, and lack the realistic controls as well.
The areas where simulators will be beneficial are mostly precedural, such as learning instrument navigation or practicing startup procedures in a new aircraft. They will be significantly less beneficial in teaching basic airmanship, even with a CFI. They cannot reproduce the sights, sounds, and feels of a real aircraft. And will FSX teach you critical safety habits such as clearing the aircraft before maneuvering, keeping your eyes outside the aircraft during VFR, or recognizing problems such as stall conditions in time to recover? No, it will condition you to fixate on all the wrong things and ignore the things that are most important for new pilots to learn.
Now I admit I am even more biased than normal against these home based simulators because I am a helicopter guy and they do not simulate them very well at all. But I would say the very same things about the more sophisticated simulators at Bell helicopter, for example, which I have also used. They are not good tools for learning the fundamentals, especially when used haphazardly at home by yourself. They are much more useful as a procedural training tool for pilots who have already learned some of the basics in the real world. This is why I believe your first experiences should be with a real instructor in a real aircraft. Save FSX for those few specific things where it can be useful, and wait until you can get some real instruction.