I am with Richard and do use Nik in most of my work. The current price (free) is a wonderful bargain (I paid around $500 for the collection when I bought it).
I personally prefer the Color Efex filters to the Viveza by a huge margin (I find Nik control points far to crude for much of what I am trying to achieve, and there are faster and easier ways to apply them, once you know how).
Where I disagree with Richard, it is just as easy to introduce artifacts when using Nik just as easily with any other editing techniques. Some of the filters, especially the Detail Extractor and Tonal Contrast can put you "over the top" with artifacts like halos all to quickly. on the other hand, used with a delicate touch, they bring out details, especially in the sky beautifully. Just as an aside, I did not use Nik tools in my edit of your image.
Now, one warning about PP work - the learning curve is long and steep and quite addictive.
