I used it for the first time recently to align a bunch of stacked vocals. The initial recordings were all pretty close to start, so not looking for big changes. In general the alignment was pretty good although I did need to do some manual fine tuning, but far less than doing it all by hand. However a few of the clips just were wacky after aligning, words way way off. Ended up doing those by hand. Couldn’t see any reason why those specific clips wouldn’t align.
I did notice that some of the (let’s call 'em) bad clips would not align correctly if they were included with other clips to align multiple clips at the same time. But if I didn’t include that clip in the multiple selection and later auto-aligned it separately on its own it aligned correctly.
Another potential gotcha is if you using the same audio in multiple places during the Project like you might in a chorus.
In any case, Render in Place is your friend when preparing to do any work that involves time stretching or pitch change.