I have to admit that even though I am a very big fan of Geezer, it just not the same without Bill Ward. I like the stuff that they've done without him, but it sounds so ordinary compared to the stuff with him. There are certain guys who always sound better when playing with their "other half". To me anyways.
There's tons of great drummers out there but there's only one Bill Ward. It's a matter of style. Brad Wilks did a professional job on the 13 album but to me his playing sounded really 'safe' for lack of a better word, maybe even 'plain'.
If they record again I really hope Bill is in the fold. For me it's just not Sabbath without him even though 13 turned out great.