The default search engine is Yahoo but you can easily change that. Flock stresses photos with built-in Flickr and Photobucket support. Not only does Flock have Live Bookmarks like Firefox but it also has a Feed reader where you can look at the articles themselves.
Flock also has built-in blogging where you can drag and drop photos. In Flock you can also favorite sites and tag them via del.icio.us. Although it works great and I really like Flock I'm not going to use it. I have a lame reason but it is important to me. The kicker was that with the live bookmarks I couldn't drag and see the RSS feeds. To see the RSS feeds you have to click every single seperate feed. I like to save time and Firefox allows me to do that.