I was accessing the new theme from my phone and could not find a link to switch to the desktop version of the site. Is it not provided intentionally because most websites provide that at the bottom of the page and it is helpful in many cases when the site is not displaying well on some phones.
There is no mobile or desktop version its only one theme thats why is called 'responsive theme'. Nopcommerce stopped using mobile theme since version 3.40
It seems there are no group products available for the new demo theme. Besides, layout problemes arise in front of complex products (with tier prices, descriptions in single products within grouped, more pictures, etc.). Can you build one or two so we see how they look like and we can test it?
This can give you an idea http://www.glamourcosmetics.it/it/flacone-dali In your sample http://new-theme-demo.nopcommerce.com/nikon-d5500-dslr there's plenty of wasted space left on the right (PC version). Rendering should be as compact as possible, as page can be very long when there are many variants, as here http://www.glamourcosmetics.it/it/flacone-miro. When trying to align three products per line, alignment can be random, due to different heights. For this reason I've developed the layout horizontally.
This can give you an idea http://www.glamourcosmetics.it/it/flacone-dali In your sample http://new-theme-demo.nopcommerce.com/nikon-d5500-dslr there's plenty of wasted space left on the right (PC version). Rendering should be as compact as possible, as page can be very long when there are many variants, as here http://www.glamourcosmetics.it/it/flacone-miro. When trying to align three products per line, alignment can be random, due to different heights. For this reason I've developed the layout horizontally.
I think the new theme layout is alot better. you can change your css and make it 100% wide. just a few entries on your styles css. probably will take less than 5 mins. I would also use slider type something for the product pics. yours are going under the social media sharing area.