This is a very simple review for a very simple product. It is nice and I love how you can scroll through the pictures for each stage. That being said it is for beginners that don't mind that nothing is actually explained. I looked at several of the pictures and wondered where they actually used a color on. This app needs a side by side view to show you how the model changed with the color selection or may just some text explaining what they did.
After looking at sites like this, you would be stupid spending $10 on this. It's neat but for something that use to be included, you would assume that they would actually include it with the box (still) or make it worth the cost. Like a real "how to". I learned more from the $10 I spent on the daemon issue of WD about painting then I did from something I bought just to paint. The paint quality is also very basic. Which I think it is what they were shooting for but they look nothing like some of the pics included in the sample images within the app.
My recommendation is either look at sites like Tale of Painters and skip the paint guide from GW. At a buck, it is well worth it. For $10, you can buy more paint. I recommend you do that. I am still a few weeks away from starting to crack open my box set but sites like Tale of Painters will probably have a lot of "how to" articles for the cost of nothing. Just look around.