What's funny is the people I know who don't know much about what happened there, all suspected the series might have been biased against the ATF because it really does make them seem really bad. And its true, it does. The shocking thing is the series actually softens up how utterly incompetent and malicious the ATF actually was. (Not intentionally, but just having to summarize events automatically makes you miss some of the sheer stupid they had to cut out.)
For example, the show makes it seem like the cease fire was due to the phone call...But in reality, the ATF shot at the house for 2 hours and ran out of ammo, and then had to ask for a cease fire to escape. It was pathetic (And they brought a FUCK ton of ammo).