These colors work incredibly together and both are amazing quality, etc. If you want to get a nail ~look like this one, it's simply simple. Do your base color, then get your glitter color and put a giant GLOB at the base of your nail. Better too much than too little. Then get any excess polish off the brush and drag up in wispy motions until it looks like a gradient. The end.
Boom Boom Pow is definitely one of the best glitter polishes I've ever used, and by far the best gold glitter polish. It looks so incredible and has so many elements to it. Kate is just a really great muted red-pink and so smooth and ~ luscious.
Kate is a little bit watery, which is usually a con for people, but actually makes it easier to apply for me (wat?). It's completely opaque either way though.
Verdict: Both super worth it imho.