The image previews load pretty fast as they are compressed to something nearing 5-10kb. The screenshot below should give you a fair idea:
The beauty of these previews is that it highlights sections of the page (in orange) with snippet containing information. The snippets highlighted are not always the same as the snippets in the search results. Click anywhere on the preview takes you directly to the site. This new change is for normal non-brand queries as well. Links from same sites can appear on 2nd, 3rd, 4th and 5th for some queries. Looks like if I site has a content, google no longer groups them, rather orders them the way it should be: PageRank.