Only thing i intensely dislike about this reader is that if you mess up and close the tab, or have a crash, and you don't recall which ePub you're reading, there's no way to go back to it. Surely there should be a way to write a local state file that would remember the previous opened file and position. Setting a bookmark is fine, but doesn't solve this issue.
If that were solved, it would be 5*.
The other issue is that if highlighting and selecting text, if you're heading towards the margin rather than away and you go a tad too far it will can it as a next/previous page activation, even though there is no click. Easy to recover from, but annoying.