GMAC Auto Insurance: Good? Bad?

I get a special rate on auto insurance with GMAC because I am a member of a national organization, and the quote was quite good. Does anybody have any experience with GMAC auto insurance? Do they service claims in a prompt, reliable way? Any horror stories?

JDPower has nothing to say about them.

Another source (good = low number in right hand column)

And Another source

That’s all I got to say 'bout that.