Well, if I understand it correctly, you can preview a page by moving the mouse over a link. If you click on a link you still have to use the back button to return to where you were. That doesn't sound like a bad thing.
But I was disturbed by the "pre-fetch" idea,
...the software pre-fetches the pages for every result and inserts a Browster icon next to each one, indicating that it's been loaded into the browser's cache.
I would prefer to NOT have my computer loading many pages into the cache just in case I might want to see some of them. If that feature can be turned off, then I might even be interested to try it.
But I'm also concerned that such ad-ins may have spy or adware of some kind and would need to know that is not true.