Anybody who has just done what I have done and read all of the 100+ posts is probably feeling pretty tired. Plus no one is going to read this any way (cause its gone for so long).
I am 22, Australian, and have been practising TKD for 4 years now (since start of 2000). I view it not as a martial sport (as some critics would categorise it) but as a full Martial Art. When all is said and done TKD has a specific focus, as all MA's do. It is not the end all MA but one that focuses the body to a particular fighting style.
Yes I would agree that some teachers will put students up into belts that they do not deserve, mostly so that the kids will come back and keep paying fees. In my club (where I help teach) we will only allow students to grade when they have demonstrated to us that they are at the right level in terms of technique understanding of the art and ability. We do have some kids who will come for the pure pleasure of being little *****, and these will usually not progress beyond a certain level.
As to the validity of TKD in real fighting. The sport like art that is pushed by most schools will not stand a chance against someone who knows what they are doing. But for those who study TKD as a proper martial art and have mastered its techniques stand a very good change of inflicting a lot of damage in a real fight. Try saying that TKD is useless in a fight to a grand master would be the TKD MA equivelant of suicide.
As for the use of kicks and punches. The kicks used in TKD its major asset. The development of TKD techniques has lead to TKD having some the most fastest and powerful kicks there are. The use of "fancy" kicks often is not necessary, but if used correctly, as they should be taught, they can have devastating consequences.
and now onto punches and blocks. The punches, blocks, stances and movements use in our patterns and fighting techniques have been developed to be as efficient and effective as possible. As stated before by other posters if your basics are excellent and learnd properly then you will evolve into a very capable fighter.
Anyway, to answer the forum question. My favorite thing about TKD is that you are taught a self defence system that is practical (if used correctly). In our club we also try to teach our kids that TKD is a means for hurting someone, and the responsibilities and consequences that come with that ability. Self control is the quintessential key to any MA. Without control you have failed to learn what most MA try to teach, that it is better to run than to fight (you don't get hurt as much).
Oh and just for your information the cut off age for TKD in Australia is 15. Junior black belts are awarded a Poom (junior black belt ranking). When they are classified as a Senior, 16, they are awarded their Dan grading.