I used this feature for my last motion graphics project and I found that it was more of a hindrance than a help. I've used AE since CS3 and was used to making sure the keyframes went in where I wanted them to go. With Auto-keyframe mode I sometimes forget to turn it off and don't realize that I've set extra keyframes until thirty minutes after, making the elimination of extra keyframes harder to find. In theory it's good, but for users that have experience with setting their own keyframes, I don't think it is too helpful.

I've used it and found John's segment on it very very helpful.  However, I would tend to agree with some folks here, it seemed more or less like a hindrance than anything else.  I would rather have it process slower and truly allow exposure or level adjustments for better edge detection or place the footage in mode that was ripe for tracking.  I found the edge detection was not at a level that was usable, even though I could clearly see the area, not sure why AE couldn't stay on track.  Really needed to spend a lot of time tweaking.  It definitely works better with HD footage over SD.  I think this tool is in it's infancy and needs to mature before anyone can truly utilize it as that "Super Tool" which is basically how it was marketed for CS5, well that and 64bit.  Lastly, when I use and see tools like Mocha that can match move very very well, I don't understand why AE's built in tools don't meet that standard.  For match moving OR stabilization.  Just seems that at this level of product and maturity for AE, they'd be there by now.  I still love AE and am seeing fruit from my labors, but I do believe they should buckle down and make these tools work better, especially when the technology is clearly there and we see others doing so.

Lastly, and I'm not one to preach..  At some point, when you continue to build on technology as Adobe has done with AE, since about ver. 6.5, new features, changed features on the same technology bed, there comes a time when you need to change the sheets.  Adobe clearly has done that, no doubt and I'm not complaining.  I do believe they are at a place now though where CS6 should have a new mattress.  So whether or not its a maturity model issue or not, I just don't think tools like these will continue to grow into these Must Have toolset's unless the new technology is adopted, out with the old in with the new type of thing and Adobe changes with it.  CS5 is a stacked version of CS4 with enhancements made to the current tools, and some additional tools like Auto-Keyframing/64-bit etc., but in reality, I'm just not feeling the love from the cost\benefit factor.

Does anyone agree or disagree with me here?  I'm curios to know if I'm a little on/off or just way outside the target area.  Cheers..

Lol..  Am I confusing Auto-Keyframe mode with the Rotobrush tool?  Sorry, I wrote that without my coffee this morning and I should have clicked on the link you provided in the first place.  Whatcanisay...  Sleeping behind the wheel.

This is a necessary feature for someone used to Shake, where this is the default behaviour.