I had high hopes for this slider, because I saw the word "responsive" in the description and was looking for something for a site I'm designing to be responsive across different viewports (desktops, tablets, smart phones, etc). The Wunderslider is not truly responsive, and you can see that from their WordPress demo page. Try narrowing the page, and you'll see that while the slider does narrow down accordingly, the height remains fixed, and the images, instead of scaling down proportionally, gets cropped. And that's even with the slider set to a Proportional setting. To me, and I think to most people, proportional means as one dimension changes (e.g., width), the other dimension (height) should change in proportion. I'm not sure what Proportional means to the Wunderslider developers; perhaps it means that you can set the width of the slider to a percentage (or proportion) of the containing object's width. If you wish to see how a responsive slider should work, take a look at Soliloquy (the one thing I don't like about Soliloquy, though, is I can't bring in my NextGen pictures; I would have to re-upload my images).
One of the good things about Wunderslider is the ease at which it integrates and displays NextGen galleries, so if you have a site with a fixed layout, and you are using NextGen as your gallery plugin, this is a very nice slider. Good transitions, overlay capabilities, and captioning.
Installation is a bit tricky. For those having problems, you download one ZIP file, but then you have to drill down deep (like three levels down) into the ZIP file to extract and upload these two folders to your plugins directory via FTP: wunderslider and wunderslider-gallery. Then go into your plugins page to activate both Wunderslider and Wunderslider Gallery.
In summary, Wunderslider is a plugin with very strong features. It's very easy to use and has a lot of options. But I think if you are just beginning with a site's design, it just makes sense to design with responsiveness in mind since that's the way web design is moving. Wunderslide falls short of being fully responsive, but I will be happy to come back to it if it ever does so.