I have several disparate feelings on this issue:
1) I think the link above is a legitimate complaint. I have given money to co-workers who did TNT - and I knew that they were getting some of their own marathon costs paid for out of my buck. I ignored the inaccurate schpeal (isn't every organization full of crap when you look at them carefully enough?), figuring that it was worth it to support a friend who was getting into running.
2) I seriously considered doing TNT for my first marathon, several years ago. For a variety of reasons, I chose not to. Later, when a colleague at work did TNT (this was the first TNT person in my life), I was eager to see how she'd do. Well, she may have been a special case, but she had a pretty tough time. She had IT band problems, got injured, tried to train injured, did her 20 mile workout while her IT band was still messed up, making it worse, was stressed that she wasn't going to be able to do it after all her effort and raising all that money, etc. The actual race was ok for her - she had the euphoria of finishing a marathon (in just under 6 hours, if I recall correctly), and of having everything turn out ok in the end.
Sure, her original goal was 4 1/2 hours, made impossible by the fact that it was Honolulu heat, and her IT band was still not fully healed by the day of the race.
After it was over, she said she'd never do that again. She stopped running.
Maybe she's a rare exception to the rule, I don't know. Of course there are many with different experiences. The others I've known had different experiences, though they also had slightly different expectations and/or backgrounds.
I have no problem with slow runners at marathons (hell, if you're reasonably fast, you can get a seed time, no? plus I imagine they will get better about race etiquette over time). I also think the net benifit to the sport at least has the potential to be positive: it'll be interesting to see how many of yesterday's penguins become tomorrow's local masters race champs.
But I know that for my friend the whole experience basically scared her off from running; even though she voiced no complaints to TNT, I feel like in some sense they failed her. Makes me just think that it's a foolish undertaking to tell people to go from 0 to 26.2 in 4 months.
If only we could inspire folks to first run decently through a 5K or 10K. The idea of a couch potato planning to within 4 months run a marathon, where they'll working at near aerobic capacity for 8 hours straight, seems like something that is really ill-advised. I have a hard enough time running at my aerobic capacity for 3 hours.