Looks great, makes a really great statement on its front page and then offers their extension for your browser... the link goes straight to the Chrome store, no other browser gets the extension support it seems
One issue is a lot more sites today have headers that block displaying the site in a frame. This prevents sites like StumbleUpon from displaying their UI at the same time as the content; the only way around it that I’m aware of is a browser extension.
Because it’s more work to maintain an extension for N browsers than to maintain a single website. So developers tend to just pick the one they care about.
And unfortunately in doing so, which is where my point really was, continue the Chromification of the internet... this seems to be counter to the theme of what they set out to do
