Pro Tests run in the order they're added to the suite
In cases where you want (I know your test cases must be atomic) where you really really want your test cases to run in a specific order, maybe if the current one rely on those of previous case, you can use Qunit by setting QUnit.config.reorder = false and your test cases will run in the order you've provided.
Pro Works really well if performing DOM Testing
All frontend developers already know the ease that jQuery framework has brought to their lives, in handling DOM events and accessing elements. Since Qunit was built as a part of jquery (is even used by jQuery itself for unit testing) hence it makes testing of DOM elements a lot easier.
Con Testing of Async operations can be a little tough at times.
Qunit, expects us to call the start() function before the Async function itself, and stop() after it stops. This can be a problem when you have no way of knowing, when your function will start or stop (your testing a number of dependent functions)