Well here's how I see it: Every country has biased commentators, but at least the Australian commentators have a good reason to sound biased. Their team has won the last 3 world cups and has been the top rated Test nation for virtually all of the last 15 years. Their side has contained guys talked about as ALL time greats: Ponting, Hayden, Gilchrist, McGrath and Warne. Bevan and Symonds in ODI cricket. So at least they are a little more justified in their constant praising of all things Australian. But if you are looking for commentators who aren't biased, you'll be looking a LONG time.
Yes, while Ian Chappell probably praises the opposition players the most (along with Tony Greig) he often gets hung up on issues that really annoy him and he comes across as pretty arrogant and unshakable in opinion. It's part of a trend I hate in the commentary box among the older commentators in particular who tend to criticise captaincy a lot. Why put out a fielder here? Why not have a leg gully? Why isn't Simon Katich bowling? Bill Lawry is forever suggesting field placings (the leg gully is his favourite) and Ian Chappell is pretty quick on the criticism button for captains too. It is only the younger breed who even bother to try and explain WHY a captain is doing what he's doing.
But while occasionally Chaps annoys me with his hard headedness, at least he discusses interesting issues and actually knows something about some of the opposition players. As opposed to Bill Lawry, who for all the words he dribbles out during a game, none of them are enlightening or particularly interesting.
70s was Chappelli's era - well captaincy era anyway, he played a bit in the 60s. I think he's fallen in love with his reputation as a great captain a bit though. He often talks about captaincy as an art and while it's often interesting to hear his take, you get the impression he thinks he knows a lot about captaincy and that he fancies himself as a pretty awesome captain. But I guess it's hard to argue with him, he does have a good record. And his abrasive/arrogant nature that many find annoying is just the way he is. I think if he'd never captained/played Test cricket, he'd be the same opinionated guy, so it's not as though success has gone to his head, it's just the way he is.