I'm trying out Flock as my default browser this week. For those that are new to Flock, it is a browser built from Firefox, but focused on adding features for social networking types of activities.  Such as built-in support for editing your blog, or adding photos to services like Flickr.

Overall, I really do like it. I haven't decided whether I'll use it as my primary browser long term. I'm going to give it more time.

General

• The aggregator (blog reader) is top notch, especially compared to most of the Linux aggregators out there. Even if I don't keep Flock as my primary browser, I'll definitely use it as a blog reader.

• Snappier than Firefox. Not as snappy as the GTK-based browsers like Epiphany and Galeon, but definitely more than Firefox. Firefox seems to feel a tad sluggish these days. Perhaps it's extension creep.
• In some parts of the interface, the fonts are very small. The font inside the blog editor entry is small. Also, on the drop down for the search box, the fonts are just tiny.
• Every Firefox extension I've tried seems to work fine. Woohoo! I've tried my must-have extensions - the Google Toolbar, Firebug, Web Developer toolbar and Adblock.
• It's a shame I can't rearrange the toolbars like Firefox. I like to move my Favorites toolbar to the right of the main dropdown menu (right of "Help"). This saves me an extra line of space. By adding folders to my Favorites toolbar, I get my own set of dropdowns. That's how I like it, anyway.

• Photo features aren't useful for me. I run my own Gallery2 photo gallery. So Flickr and Photobucket support doesn't do anything for me. I'm sure this can be extended, and Gallery2 support would rock, but for now the features are turned off for me.
• The back button doesn't have the nice down arrow to show a history list.  I eventually realized that a right-click show it, but that was a total lucky guess by me.  I suspect most will never find that feature unless told.
• Cool icon
• Very nice default theme.  I think I prefer it to any Firefox theme I've found.  It fits well with my current Gnome desktop theme (Candido Light).
• I tried hard, but I can't get any video plugin support working under Linux.  Same for Java plugin support.  I have these working in Firefox and other Mozilla-based browsers.  I know it's because I manually installed Flock (had to) but manually linking in the plugins doesn't improve the situation.  Flash is the only thing that was recognized and installed.

Favorites

The favorites have been my biggest transition pain point, so I'm going to cover why.

• At first, my Favorites Toolbar showed nothing, and I couldn't right click on it. After I took all the contents out, and put my own contents in, it started working. Not sure why.
• Having both tagging and collections is confusing. I'd personally prefer to just have tags, and then have folders that are made up of tags.
• Took a bit of getting used to not being able to have multiple levels of folders. I think if this were to be pure tagged-based, this would make more sense. But a collection is easily construed as a folder, yet less powerful because I can't have a hierchy.
• Why does the Favorites and the aggregator (which are fundamentally similar paradigms) have such different functionality? No tagging in the aggregator (Google Reader has tagging, so it's not unheard of). Yet, the aggregator supports multiple levels of hierchy, which you wouldn't with tagging (more of a semantic topic map concept, any node can be in multiple places at once. Again, this is how Google Reader is).
• The only way to make tags useful is through search, so the search shouldn't be all the way at the bottom. Perhaps this is less important if you drop categories and tags become the folders. Still probably should be at the top though.
• I really like being able to add Favorite folders to my Favorite toolbar in Firefox. This allows you to create custom drop downs of your bookmarks. I find this to be a huge productivity benefit.
• The bookmark manager can at times go in to hard loops, and sometimes even deadlock. Especially when trying to drag and drop.

Blog Editor

• Simple, but does the job.
• As I mentioned, font's are small in the editor.
• Blog editor should have support for basic semantic tags, like H1 H2 H3. Right now, I have to switch to source view.
• On the blog editor, some way to add custom markups would becool. I frequently use <span class="code"> to surround my codeblocks on blog postings.
• No (wysiwg) image support. :(
• I easily managed to screw this blog entry (my first in Flock) all to hell. I had to go into a text editor and fix the mess.