I think they do an excellent job, easily the best by some distance. For people that criticise them, try and talk continuously for 3 hours about what's going on in front of you that isn't always the most entertaining, in fact put an audition tape together and upload it to YouTube and give us all a laugh. It's a difficult balance to strike of being informative and entertaining. If I did have a criticism it would be that they don't often go into enough detail, but then maybe they are told to keep it quite superficial, I don't know.
The days of Richie Benaud saying 1 sentence once every over in cricket or Dan Mascal saying "Oh I say" at the end of a rally in Tennis are of the distant past.