That's a good blog indeed. Markdown led me there ages ago, and I've been a regular since. BTW, probably the word you were looking for is systemic, not systematic.
You've got it wrong. He's not nearly as bad as some of the Apple commentators out there. He is consistent with his praise as well as his complaints. He close enough to the employees to add an accurate insight, but detached enough to maintain an in-bias view.
There isn't another Apple reviewer I trust more than Gruber.
In an unrelated anecdote I thought I'd share about daringfireball.net is that I used to do domain research for SEO purposes and sifting through each expired domain from the major registrars I was absolutely shocked as to how many links come from that domain.
He has linked to so many failed website and startup ideas over the time that I literally saw a link from his blog at least once a week.
His website may be one of the most prodigious spreaders of decent link-juice on the internet.
You've got it wrong. Just because he is not as bad as other apple commentators and him having some complains doesn't make him unbiased. His pro apple bias made me stop reading his blog.
Also: Yes, he created markdown. Mad respect for that!
Likewise for the Macalope's column.