Ha... spent the whole game NOT parrying stuff. The only other boss who gave me a major issue was Manus in the DLC, the rest I used my mobility to dodge and counter.
Gwyn is actually quite easy compared to a bunch of the other bosses, all his attacks are parryable so you can kill him in about 30 seconds if you can get the timing down.
Wait till you get started on DS2 :D
I just got up to Gwyn on DS1 and I'm about ready to throw my house out the window.