Hmmmm i wouldnt say that Ninja 2 is not useful, its a great dvd and Brad Christian is an excellent teacher. There are some very useful sleights taught on there and some excellent effects, but for me personally, i had learnt effects that i would prefer to perform rather than the tricks on Ninja 2. Please dont let this put you off though, as it is definitely a very worthwhile purchase to add to your collection. So yes i would agree with the recommendations to go with both Ninja's, you will not be disappointed trust me.
Also be aware, Chad Nelsons clipshift, whilst being a great utility move and makes some great effects possible, is not an easy sleight to master! Ive been working on it for nearly 6 months now and ive only just got to the point where i would be comfortable perform it for a small group!!
Hope this helps,
Tommy