I use RunKeeper, which lets me input the program in myself and choose the tunes I want played when I run. I am also lazy tracking where I run (and see how far I've gone) and that nifty app tells me how many km/mi I ran, how fast I went per interval. I am looking ahead than C25K, which is why I got this app. I'm also doing a modified version fo the C25K, so that's another reason I got the app.

I have and tried the C25K app (brown one) and enjoyed it for its purpose. It doesn't let you pick your music, but you can certainly have your iTunes on first, and run the app so you can have your music. I find the voice over and the buzz sound too loud for my taste. My 2cents: definitely get the C25K app if your goal is just to go for that and find other means of tracking after your program. If you would like something that you can also use at other times (RunKeeper lets you input other activities you did --biking, hiking, etc), get RunKeeper.