As a lefty, I dislike them. Ergonmically, I didn't find them any better or worse than a standard rifle. My only experience with bullpup are the Steyr AUG and the Walther G22.
Steyr was okay, but the walther was a total POC.
I know a lot of models are being offered in true Ambi, like the RFB, or lefty models. The mag change never feels right, IMO.