I have been looking into a couple of other strength training/ conditioning apps (Jillian Michaels Slim Down and BodyFitness) previously, but just didn't like them that much. I found them nice to get new ideas for strength exercises, but other than for inspiration or as reference, I might never use those apps again.
What I was always missing was a voice-guided exercise that I can just follow, without having to go back to my phone and check what the next move was. That was the reason why I downloaded NTC in the first place, because it promised just that.
Note: all screen shots are taking from the app store website