Back button? Gone, and replaced by a left swipe. Refresh button? Gone, and replaced by a down swipe. Address bar? Menu buttons? Gone. Coast does away with everything but a home button and a recently viewed button, both of which have been moved to the bottom of the screen. All the other buttons and commands were replaced by gestures, many of which you have probably already learned.
In short, Coast does away with the many parts of a web browser that were inherited from desktop browsers but never really worked well on a tablet.
When you open Coast for the first time, you're shown a launch page with a search bar and icons for frequently accessed sites. You can add your sites by searching or entering the URL, and you can rearrange the icons by simply dragging them around.
I have been playing with Coast for the afternoon and I can see that it is immediately more usable than any of the other web browsers on the iPad. This will be the web browser that will have everyone else scrambling to study and copy. And IMO this, folks, is what Apple should have released on the iPad when it launched.
But as I sit here editing this post I have noticed one rather interesting design choice. Coast doesn't have tabs, which might be a problem for when you want to quickly switch between several sites. But Coast makes up for this by having webpages continue to be active after you return to the launch page. Youtube, for example, continued to play a video after I left.
This is going to present a problem for security and usability. If closing a tab won't log you out of the activity then either we'll have to change our browsing behavior or Coast might need to be tweaked.
There's no word yet on when Opera will release an iPhone or Android version of Coast, and I think it can't happen soon enough. When Coast hits Android it could well be the app that brings Android tablet owners back online again.
The app is free in iTunes, and is stable for a 1.0 release. I only noticed a few minor CSS errors on the websites I visited.