I find Paul McGinley poor, can't take to him atall. Very much like Mark Roe he won't say things bad about certain players but will have snide digs at others. Rich beem and Wayne Riley are great, butch in fact most of the sky team are, just the two mentioned previously I don't find very goodTo me golf and cricket commentators these days do more than just describe the action (ie, what the viewer can see), they are generally ex players and so can pick up on things that the untrained eye can't see eg, difficulty of shot, tactics etc.
Also, i want a commentator to be willing to criticise when appropiate and not sugar coat stuff - if you want to be everyones buddy, dont become a commentator.
Specifically to golf i think Paul McGinley adds something as he is quite opinionated and has strong views that he is prepared to say, and also calls a bad shot, a bad shot - whereas Ewen Murray too often looks to make excuses when a player hits a poor shot instead of calling it for what it is - and also at times gives too much credit, ie, praising spin control when a player was simply hoping to reach the green.