I have been using a variety of HDR programs: Photomatix, Photoshop CS5's Merge to HDR Pro, and HDR Photostudio (now HDR Expose). Each has its own strengths and foibles, and I've learned which images work best for me in which program. I generally go for the most natural look.
I just downloaded the NIK HDR Efex Pro, trial version. It rocks! The first part, merging to an HDR 32-bit file, is automatic, with a few choices to make concerning ghost removal, alignment, etc. When the Begin Tonemapping button is pushed, your image comes up as a very large preview, with some 34 or so presets on the left side that can act as starting points, with a wide range of HDR effects. On the right side of the screen is a panel that looks very much like Viveza, with global sliders for exposure, contrast, structure, saturation, warmth, HDR method and HDR strength, among others.
There are also control points with the same sliders available, and they really work in selective parts of your image...the first I have seen in HDR programs with this available. There are some other effects possible in the right hand panel including levels/curves and vignetting. I haven't become familiar enough with all of the choices yet, so there may be more that I don't remember at this point.
The main things are: 1) After trying with image sequences that I had problems with using other programs, NIK seems to do at least as well in terms of artifacts and over all effect. 2) The adjustments are so intuitive (especially if you know Viveza or Silver Efex Pro) and locally controllable that my wallet is beginning to itch, badly!
Disclaimer: I do not work for NIK, nor am I related to anybody that does.
Claimer: I use several of the NIK programs and find them indispensable in my workflow.