From what I've read over almost a decade of online debates is this:
Bullpups are advantageous in CQC thanks to their shorter overall length, but since the trigger is not directly connected to the mechanism the trigger pull is usually just not as good as a rifle of conventional layout. They can also be more difficult to fire from the prone position because the magazine is sticking out. Lastly, people who have used a lot of firearms of the conventional layout seem to have a bit of difficulty adjusting to reloading and handling bullpups.
That's just what I've heard, I've never had a chance to actually fire a bullpup rifle yet.
"Mankind, when left to themselves, are unfit for their own government." - George Washington